Running G4.5 on Windows Vista Home Premium 64-bit, works great, no issues at all. BTW, the IT guy that said no reason unless you've got 64-bit apps wasn't comepletely correct, a 64-bit OS can isolate memory and keep a nasty application from taking out the OS, you'll have far fewer (if any) system lock ups or application freezes with a 64-bit OS...

Jack