What is your budget? The prices range from $5000+ to $1200 as a minimum. My comp cost around $1500 total (with all the upgrades I did) and it plays all games at the highest settings that my monitor can support (1280x1024). Of course, I've oc'ed to make it that way, but there you go. A case doesn't really matter. Unless you like to show off (which can be tempting) spending $100-200 on a case is really dumb. The mobo is all about amd, and the cpu too. Intel just isn't a game cpu and mobo company. For gaming, you hafta to go with amd, preferablly the new socket 939, which is upgradable to the new dual cores (two cpu's instead of one). A good cpu for amd is like mine: an amd 64 3500+. The cpu's go from 3000+ all the way to 4000+ and then to fastest cpu in the world: the fx-57. THe dual cores just came out and sport faster speeds (two cpu's) but for games, you want just one cpu. Trust me. Anyways, mobo is important because sli is out (scalabe link interface) where you can connect two graphic cards instead of just one. I've seen benchmarks... trust me. For graphics, in the upper range that is, sli is the way to go. Dual 6800 gt's destroy all competition unless you have dual 7800's, the best graphic card out today. I have an x800 (my mobo was built for ati) but it runs well and I have no lag at all. You'll want an audigy gamer z2s for sound, to process it. Yeah. As for an OS, Pro is the way to go, as of it's fast and secure. I have windows media center (I watch and record t.v. on my comp) but pro is something to look into. For lower end stuff... cpu is a good 3200+ (if you oc) or a 3500+. A lower end graphics card is like mine or a 6600gt or even a 6200 (which really sux... but hey, it does its job for all)(lol). Hope this helps!