For the miniscule price difference, I always go Pro. With the new dualcore's coming out, it will require Pro anyway.
Plus, using wireless and a laptop, you can run an XLR cable into the next room, and use the laptop to remotely control your DAW without the fan hum, if that's an issue. Kinda cool.
I use remote desktop all day long at work, and at home. I'll be sitting downstairs sipping coffee doing Reason/Tracktion work on my laptop, and be encoding DVD's upstairs on my desktop.
OEM difference is usually like $40.
As for 2K3 Server for DAW......unless you have a bootleg copy (which is a super bad idea, since 2K3 "calls home" more than XP does) which is wrong, IMO, buying a $500 OS (SBS) for a DAW seems retarded.