Here are the parts I have in mind. They are compatible, right? Is the case unnecessary? (I might add another 4870 later), or can I go with the antec 900? Antec Twelve Hundred Black Steel ATX Full Tower Computer Case GIGABYTE GA-EX58-UD3R LGA 1366 Intel X58 ATX Intel Motherboard Intel Core i7 920 COOLER MASTER V8 Seagate Barracuda 7200.11 ST31500341AS 1.5TB Radeon HD 4870 OCZ Gold 6GB (3 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) CORSAIR CMPSU-750HX 750W PSU Arctic Silver CMQ-22G Any DVD drive
A 900 is fine, but I would strongly recommend the Nine Hundred Two as it is a much better design than the original, which has several major flaws. The Tuniq Tower and Noctua NH-U12P are much better coolers than the Coolermaster V8.
Most manufacturers provide bolt through kits for i7 on existing coolers, I imagine Tuniq probably do for theirs. Noctua have made their own i7 version of their NH-U12P cooler. Thermalright have done the same, but Newegg don't sell Thermalright products.