I would recommend using robocopy instead of VBScript. Robocopy does this by default. If is part of the Windows 2000 resource kit.
Robocopy was included in the OS starting in Windows XP forward. The existing switches in one version are generally the same across newer versions. Add a check in your script for robocopy and copy to the system if not present (you may want to include OS version checking). Then you can use it to manage your copying. Great thing is robocopy provides a logging facility.