I am going to be ordering a low cost computer (<$500) to do rendering for me at home. With the limited budget, I will probably get a Dell server (SC420) or something similar that I can add a larger hard drive to down the road. My question is about RAM speed, will there be a noticeable difference between 400 MHz and 500 MHz RAM for my long renders? Does anyone have any other suggestions for something to do exclusively rendering in this low range? I just can't keep giving up my computer for days at a time while it crunches out frames.
I would go with quantity for amount of ram versus thinking along the lines of "speed." Chances are you will not notice any difference between 400 or 500mhz ram. You will notice a difference between 512meg versus 2-4gigs of ram. That will allow more elbow room for your rendering engine of choice to do its thing. Also I know your budget is tight, but you may want to seriously consider getting a box that is dual processor capable. That way down the road you can pop in another processor and almost double your performance.
My .02
GL and HF 
there was an article on gamepc.com a while ago that investigated different speeds and settings for ram and the effect they had on a whole bunch of stuff... rendering included.. basically it seems that these days ram speed cas latency etc etc makes so little difference that you are far better served spending your money on more ram than faster ram
If you get an athlon 64 you should be able to pop a dual core in laterdown the road...
(sorry i dont know which specifc sockets you need for this off the top of my head)
Thanks for the replies. It is good to know that ram amount is much more important than ram speed. I ended up getting a poweredge that is a p4, 2.8 with 512 RAM for about $380. I will try to upgrade it to 1G. I would have really liked to get something that was dual processor capable, but that will have to happen later when I have a little more money to invest. Right now I don't do enough rendering to warrant more power. This should be fine as long as I keep it running in the background while I work on my main computer. Thanks again for the advice.
0.5 g is a bit little 1 G is bare minimum, better teake 1.5