I've rarely had a file transfer problem with XP, it has been surprisingly stable on the frequent occasions I have to use it for programs like adobe Premiere etc etc...
However, I'm sure many agree it's not a choice for someone looking for rock solid performance, proper usable security etc... Especially when you consider that M$ likes to word their EULA's to their benefit (see their .NET Passport ToU about proprietry works and then never use Hotmail or M$N Messenger for any important communications again!
If money weren't a consideration I'd go out and buy a new Dual PowerMac G5 tomorrow, but it is, and I don't even have the $600 (or UK equivalent) for an eMac over here (and I wouldn't get one because my Linux box outperforms a G3 anyway - better to scrimp together for a faster Mac).
Pity software vendors like Newtek and Adobe won't develop for the Linux platform (Lightwave only offers the rendering core for Linux, not the editor applications, again requiring the use of Windows).
Sigh...