Creating Outlook XP profile from .PRF file

I'm trying to automatically create profiles for all users in our Outlook XP
installation using a modified .PRF file as the source. The profile gets
created fine with correct server and mailbox, but I am unable to get the
profile name to match the user's logon name. I've tried using the following
line in the General section of the .PRF file, which I'm pretty sure has
worked in past versions of Outlook (with Newprof.exe)

ProfileName=%USERNAME%

but it doesn't seem to recognize variables in this General section, even
though the same variable is used later in the .prf file to identify the
mailbox.

Has anyone had success doing this in XP?

Thanks,

David Finnegan