If you're bumping up against your budget, I would check your local craigslist for near new stuff. A guy had the 550 cpu for only $50 yesterday here in austin. I use frys combo specials; I'm not too picky about the motherboard. Newegg has an email promo today that includes a basic rosewill atx case with 120mm fan for $21.xx shipped. A great deal. A decent 500-600w ps is what you need; make sure it's 80% efficient.