I kind of cheat here. I'm primarily a software person, not a hardware person. But I have a friend who builds custom PCs for a living, so whenever I want something new, I just go over it with him and he builds it for me. The custom gaming PC I'm on now was built by him and it's pretty darn good. I commissioned it about a year ago to be able to run The Sims 3 in "ultra mode." I specify the minimum processor, RAM, and hard drives I want, then let him do the rest.