So, a friend has an opteron server - 4 model 846s, to be exact, which he has been planning on using to redo his main webserver. Apparently he either got really curious, or he is serious about it, but he messaged me and asked:
"Does XP Pro support 4 processors?"
That'll be one monster workstation - too bad the video will be PCI.
I did some poking, and recomended using w2k server as the OS. Obviously, he'll need to turn off a bunch of services. 2003 server has, from what I've heard, some compatability issues with some desktop software (games), even if you enable hardware acceleration. I may fire up my copy to check these rumors out.
Of course, he should run linux on the box... but then the games, and 3d modeling/rendering software he is so interested in won't work anyway.