It really all depends on your budget and what you want to do with your computer. Personally, I am getting ready to build a high-end custom computer that was featured in the Sept 2010 Maximum PC issue. My Mac Pro will be made part of my render farm for me to use with other programs like Vue, C4D, etc.

In regard to what version of Windows 7, you will need "Pro" or "Ultimate" if you want to run more than one CPU. Also, you are limited to 16GB of RAM with Home but not the others. Certainly you want to be 64 bit all the way.

Besides CPUs, a very good graphics card, you will want at least 10GB of RAM or more. Also, I would suggest maybe looking into an SSD for the programs and a good hard drive like the WD Carvier "Black" for speed and mass storage. Your read/write speeds are VERY important and a good hard drive or SSD will be great for performance.

Also, if doing a render farm, I recommend to go with full CAT 6 (NOT 5e) hard wired solution for all the nodes that are part of your network.

Most of the other advice I think has been covered pretty well by others. Good luck and happy rendering.

Jeff

Development on: Mac Pro 2008, Duel-Boot OS - Snow Leopard 10.6.6 & Windows 7 Ultimate 64bit, 2 x 2.8 GHz Quad-Core Intel Xeon , 10GB 800 MHz DDR2 RAM, NVIDIA GeForce 8800GT.