Don't use a batch file.

You state that the workstations are XP. NT/2000/XP do not require the use of a batch file.

Place the logon script into their account settings.

Unless you really want/must run it via GPO, in which case you might have to use a batch file. In that case though it goes into the NETLOGON not the path you see above for scripts.

That may not be the fully correct information, but since we have a mix of client OS I was not able to get the logon script to work for ALL OS by leaving in the scripts folder. You may be able to if all your clients are XP though.