I use VB to update a marker file in the root of the C:\ drive. An example file is called Build-xp.01.01.000 and the 000 will go to 001 ' Rename the build marker file OPTION EXPLICIT Dim fso Dim Folder, OldFile,NewFile, FileColl Dim MajorMinor Dim BuildNumber Dim FolderPath Set fso = CreateObject("Scripting.FileSystemObject") wscript.echo "Finding Marker file" FolderPath = "..\XP With SP1\$OEM$\$1" Set Folder = fso.GetFolder(FolderPath) Set FileColl = Folder.Files For Each OldFile in FileColl If Left(OldFile.name,8)="Build-XP" Then WScript.echo "Old Marker " & OldFile.Name MajorMinor = Left(OldFile.name,14) BuildNumber = Right(OldFile.Name,3) BuildNumber = BuildNumber + 1 NewFile = MajorMinor & "." & Right("000" & BuildNumber,3) WScript.Echo "Renaming to " & NewFile fso.MoveFile FolderPath & "\" & OldFile.Name, FolderPath & "\" & NewFile Exit For End If Next Set fso=Nothing wscript.echo "Finished" This gets called as part of the ISO Creation command file using: ECHO Updating Build Number CSCRIPT RENAME.VBS ECHO Creating ISO...