video compression machine

Hi,
I am setting up a PC for crunching through video compression, but honestly, I have only done Mac setups before when it comes to video stuff, and I am not totally into the tech side of computer hardware, for that matter.

Due to constraints in budget, we will only have the adobe suite installed, which means I will be using after effects for batch compressing these videos.

Can anyone recommend me a good setup for doing this? It has to be a single PC (no render farms, unfortunately) The computer may occasionally be used for editing, but mostly just crunching through video compression as fast as possible.

What are the main things to look at there, just processor speeds and RAM? Is there anything else to take into consideration?

Thanks,
CW