I have a small "renderfarm" myself and am using a Mac Pro for the main computer while the other two systems are my render nodes. Right now I have it setup with Windows 7 64bit on all computers and I can tell you it is VERY fast and helps with the LARGE scenes or animations.

But the answer is not going to be one you want to hear I am afraid. While one of my systems is an older AMD FX55 running Windows 7 64bit with 2GB, the other is an I7 with 6GB and the main system, the Mac Pro has 10GB. Therefore you are going to need at least one VERY good main system and one very decent 2nd system. The others won't really slow you down that much, or at least should not and are simply added to the chain. Sort of think of it like SETI At Home type of use where a lot of computers peck away at a task.

The bottom line is the other posters are right and I would advise you to just save your money for better hardware because the specs you posted will NOT begin to cut the mustard for anything very useful. Sorry, but that really is the best advice for right now given what you have posted.

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.