antec 900, or 1200 is a solid case.... i have the Cooler Master Stacker 832 and its huge and will fit anything inside it and has extreme air cooling capabilities. any case with atleast three 120mm fans should do you well. 6 120mm fans would be prefered but would be more expensive. If i were you i would have my set up as follows:
intel e8400 or q6600 and OC them about 30% or more if you desire.
4870, 4850x2, 4870x2, gtx 260, 9800gx2 gtx 280 either one of those, price is the only concern in that.
an Asus mobo i always use when building high quality PCs. I find them the most trusted ive had experience with. any x38 or x48 asus motherboard or an asus p45 mobo such as a P45Q Pro or Deluxe or the ddr3 version if you decide to go that route.
for ram i would recomend 2-4 gigs, 4 prefered will make your pc stay ontop of current games longer. good brands are mushkin, Crossair, kingston, geil, patriot, crucial, OCZ, get a kit with heat spreaders which is a thermal heatsink that covers the ram. Dont buy value ram its cheep and slow. ram with lower timings are faster and better such as 4-4-4-12 compared to 5-5-5-18 the first one is faster unless their speeds are different. any ram above 1066mhz should do you well. i have 2 gigs of OCZ flex 1200mhz 5-5-5-18 which are set at 1066mhz 4-4-4-12 with my cpu OCed 30% which is nice.
get a 20x sata dvd burner.
i dont think you need a 1tb hdd. i have a 250gig sata and its fine. unless you have tons of games you shouldnt need more than 250gigs. i have a seagate hdd which is real fast and ive had WD hdds and their nice too, also ive herd about the seagate 7200.11 hdds which are amazingly fast but i have not tried them personally. if you want even more speed get two 250hdds and set them in a raid 0 array and itll boots your performance through the roof.
get a good cpu cooler if you plan to OC a zalman 9700 is good, or a thermalright ultra 120 is also good.
