MAKE SURE YOU GET Windoze XP PRO… home edition dose not use smp for multithreading… the server edition also allows for smp, and 64 bit extensions (might be only for Itanium INTEL chips)
Max, Maya, Photo shop,all have plans for 64Bit versions… they will be using Windoze 64…
Think Maya and XSI both have versions that run under 64 bit linux… if not I know they all run under wine (in 32Bit)…
Z2 might also run in wine, I have not tried… I don’t think they want us using it in other OS according to the licence…
I am keeping my Intel system for content creation and video games and the Opteron system is strictly for rendering… I dont think I am even going to install Z2 on it after I upgrade to XP home (I might install it just for benchmark, then remove it …) it is probably going to be running Fedora core most of the time, this way I can run Linux using Black Box, or IceWM this way I can run true space with all system recources… I tested true space in WINE and it is amazing!!! I am going to test it in Windows XP this afternoon… the fastest OS is the one I will keep running 
If you guys are running network anb need windows box to talk to a *Nix box try using SAMBA… there is even a tweak to use on a CISCO LINK SYS routers LMAO!!! that has got to piss Cisco off… they hate Linux 
they make UNIX and lawsuits against LINUX…
anyways…
If you guys are running Linux, also DON’T buy ATI graphics cards… Nvidia is only people who make 64bit LINUX drivers… both ATI and Nvidia make 64bit windows versions…ati has Linux drivers also but only for 32bit OS…
I did not look into the sound drivers yet, but if you want sound on your system in 64bit LINUX or WINDOWS, you better look at website first… My system I just had sound blaster Audigy put into it I knew there was windows 64 bit drivers … I really dont ever plan on having sound on that system tho… it is a work horse… My show pony is is still fast enough to keep me happy in Zbrush, and for all my game and sound needs… you guys better check first tho before you make a buy 
The opteron is just there as a rendering machine, If I have some major Huge Zbrush document I need rendered, I might install Z2 over there… but for now I am happy with my current system Z2 renders amazingly fast in the first place :)…PLus I like takeing a break and watching it render ;).