Por si en algun momento lo intentan se encontraran con algun que otro 
incoveniente para visualizar un .evt exportado de Windows 2003 en un Windows Vista.
En el siguiente link se muestran varias soluciones aunque creo la mejor es utilizar
el Script abajo mencionado , ya que nos generara una opcion en el menu Contextual.

Aqui esta el Link

'==========================================================================
'
' NAME: ConvertEVTtoEVTX.vbs
'
' AUTHOR: Steve Paruszkiewicz, Microsoft
' DATE  : 10/04/2007
'
' COMMENT:  Adds "Convert to .EVTX" to the shell context menu for .evt files
'            calls wevtutil to convert evt file for use on Vista/Longhorn
'             then opens the converted .evtx file in event viewer
'
'            If you would later like to remove the Convert to .EVTX context
'            menu option you can delete the following registry key
'            "HKEY_CLASSES_ROOT\evtfile\shell\Convert to .EVTX\"
'==========================================================================
Option Explicit
Const LAST_MODIFIED = "10/11/2007"
Const AUTO_OPEN_EVTX = True            
'Set this to False if you want to be prompted to open the converted file instead of 
'opening autmatically


'On Error Resume Next
CheckReg()                                                
'Check to see if script is already registered - NEEDS ADMIN TOKEN ON VISTA


If WScript.Arguments.Count < 1 Then ExitScript("** No File Argument Specified **" & VbCrLf & _ 
 "Script Exiting..." & VbCrLf & VbCrLf & "Convert to .EVTX has been added to the context menu")

Dim strInputFile : strInputFile = WScript.Arguments(0)

ConvertEvtToEVTx(strInputFile)



'************************   Subs and Functions ****************************
Sub ConvertEvtToEVTx(strFileName)
    Dim Shell : Set Shell = CreateObject("Wscript.Shell")
    Dim FSO : Set FSO = CreateObject("Scripting.FileSystemObject")
    Dim strCommand, ret, shortname
    
    If Not(FSO.FileExists(strFileName & "x")) Then
        
        strCommand = "wevtutil export-log """ & strFileName & """ """ & strFileName & "x"" /lf"
    
        WScript.Echo "Converting " & strFileName & "  to .EVTX file"
    
        Shell.Run strCommand,0,True
    
    Else
        shortname = Right(strFileName,Len(strFileName)-InStrRev(strFilename,"\"))
        ret = MsgBox ("The file: " & shortname & "x" & VbCrLf & VbCrLf & "Already Exists." & VbCrLf & _ 
                       "Would you like to overwrite it?",vbYesNo+vbInformation,"File exists")

        If ret = vbYes Then
            strCommand = "wevtutil export-log """ & strFileName & """ """ & strFileName & "x"" /lf /ow:true"
            WScript.Echo "Converting " & strFileName & "  to .EVTX file"
    
            Shell.Run strCommand,0,True
    
        Else
            WScript.Echo "File already exists:  Skipping conversion."
        End If
    
    End If    
    
    WScript.Echo "WEvtUtil Command Done."
    
    If AUTO_OPEN_EVTX Then
    
        If fso.FileExists(strFileName & "x") Then 
            Shell.Run "eventvwr.exe /l:""" & strFileName & "x"""
        Else
            MsgBox "The EVTX file: " & strFileName & VbCrLf & VbCrLf & "Could not be created. " & VbCrLf & _ 
            " Please check drive space and permissions on the target folder." & VbCrLf & VbCrLf & "Script Exiting..." _ 
            ,vbOKOnly+vbExclamation,"Error"
            WScript.Quit
        End If     
        
    Else
        ret = MsgBox ("Would you like to open the .EVTX file now?",vbYesNo+vbInformation,"Conversion complete.")
        If ret = vbYes then
            
            If fso.FileExists(strFileName & "x") Then 
                Shell.Run "eventvwr.exe /l:""" & strFileName & "x"""
            Else
                MsgBox "The EVTX file: " & strFileName & VbCrLf & VbCrLf & "Could not be created. " & VbCrLf & _ 
                " Please check drive space and permissions on the target folder." & VbCrLf & VbCrLf & "Script Exiting..." _ 
                ,vbOKOnly+vbExclamation,"Error"
                WScript.Quit
            End If     
            
            Shell.Run "eventvwr.exe /l:""" & strFileName & "x"""
            
        Else
        
            WScript.Quit
            
        End If
    End If
            
End Sub 



'*** Checks to see if script has already registered right-click menu entries
Function CheckReg()
    On Error Resume next
    Dim retval, Shell : Set Shell = CreateObject("WScript.Shell")
    retval = Shell.RegRead("HKEY_CLASSES_ROOT\evtfile\shell\Convert to .EVTX\command\")
    
    If Err.Number <> 0 Then
        'WScript.Echo Err.Description & "  " & Err.Number
        Err.Clear
        AddSelfToReg()                                                    
'adds ability to run from context menu

    End If
End Function

Sub AddSelfToReg()
    ElevateThisScript()
    On Error Resume Next
    Dim strCommand, Shell
    
    Set Shell = CreateObject("WScript.Shell")
    If IsWin64bit() Then
        'Use 32-bit wscript.exe to overcome problems creating excel.application object when passing in a file on x64
        strCommand = Shell.ExpandEnvironmentStrings("%systemroot%") & "\SysWOW64\cscript.exe """ & _
        WScript.ScriptFullName & """ ""%1"""
    Else
        strCommand = Shell.ExpandEnvironmentStrings("%systemroot%") & "\System32\cscript.exe """ & _
        WScript.ScriptFullName & """ ""%1"""
    End If
    
    Shell.RegWrite "HKEY_CLASSES_ROOT\evtfile\shell\Convert to .EVTX\command\",strCommand,"REG_SZ"
        
    If Err.Number <> 0 Then
            ExitScript("Unable to write to HKEY_CLASSES_ROOT " & VbCrLf & _
            "This Script may need to be run with a full administrative token once to register context menu entries.")
    End If
End Sub

Function IsWin64bit()
    On Error Resume Next
    Dim fso : Set fso = CreateObject("Scripting.FileSystemObject")
    Dim shell : Set shell = CreateObject("wscript.shell")
    Dim Windir : Windir = shell.ExpandEnvironmentStrings("%SYSTEMROOT%")
    If fso.FolderExists(Windir & "\SysWOW64") Then
        IsWin64bit = True
    Else
        IsWin64bit = False
    End If
End Function

Sub ExitScript(ByVal MSG)
  Msg = Msg & VbCrLf
  Msg = Msg & "_______________________________________________________" & vbCrLf 
  Msg = Msg & "VBS script created by Steve Paruszkiewicz. Last modified on: " & LAST_MODIFIED & vbCrLf & VbCrLf
  DisplayMsg(Msg)
  wscript.quit   
End Sub

Sub DisplayMsg(Msg)
      On error resume Next
    Msgbox Msg
End Sub

'*********************************************************************************
'    Subroutine: ElevateThisScript()    
'
'    Author: Steve Paruszkiewicz, Microsoft
'    Last Modified:  August 2, 2007
'    
'    Purpose: (Intended for Vista and Windows Server 2008)
'    Forces the currently running script to prompt for UAC elevation if it detects
'    that the current user credentials do not have administrative priviliges
'
'    If run on Windows XP this script will cause the RunAs dialog to appear if the user
'    does not have administrative rights, giving the opportunity to run as an administrator  
'
'    This Sub Attempts to call the script with its original arguments.  Arguments that contain a space
'    will be wrapped in double quotes when the script calls itself again.
'
'    Usage:  Add a call to this sub (ElevateThisScript) to the beginning of your script to ensure
'            that the script gets an administrative token
'**********************************************************************************        
Sub ElevateThisScript()
    
    Const HKEY_CLASSES_ROOT  = &H80000000
    Const HKEY_CURRENT_USER  = &H80000001
    Const HKEY_LOCAL_MACHINE = &H80000002
    Const HKEY_USERS         = &H80000003
    const KEY_QUERY_VALUE      = 1
    Const KEY_SET_VALUE          = 2

    Dim scriptEngine, engineFolder, argString, arg, Args, scriptCommand, HasRequiredRegAccess
    Dim objShellApp : Set objShellApp = CreateObject("Shell.Application")
        
    
    scriptEngine = Ucase(Mid(Wscript.FullName,InstrRev(Wscript.FullName,"\")+1))
    engineFolder = Left(Wscript.FullName,InstrRev(Wscript.FullName,"\"))
    argString = ""
    
    Set Args = Wscript.Arguments
    
    For each arg in Args                        'loop though argument array as a collection to rebuild argument string
        If instr(arg," ") > 0 Then arg = """" & arg & """"    'if the argument contains a space wrap it in double quotes
        argString = argString & " " & Arg
    Next

    scriptCommand = engineFolder & scriptEngine
        
    Dim strComputer : strComputer = "."
        
    Dim objReg, bHasAccessRight
    Set objReg=GetObject("winmgmts:"_
        & "{impersonationLevel=impersonate}!\\" &_ 
        strComputer & "\root\default:StdRegProv")
    

    'Check for administrative registry access rights
    objReg.CheckAccess HKEY_LOCAL_MACHINE, "System\CurrentControlSet\Control\CrashControl", _
        KEY_SET_VALUE, bHasAccessRight
    
    If bHasAccessRight = True Then
    
        HasRequiredRegAccess = True
        Exit Sub
        
    Else
        
        HasRequiredRegAccess = False
        objShellApp.ShellExecute scriptCommand, " """ & Wscript.ScriptFullName & """" & argString, "", "runas"
        WScript.Quit
    End If
        
    
End Sub

Once you have the script installed, right click on a .EVT file and you should have the option to convert the file to .EVTX format as shown below: