since you're going with a black edition CPU it only makes sense that you're overclocking, and like gordon said the 955 and 965 overclock exactly the same, the 955 is just cheaper. the PSU is WAY overkill, 650W is more than enough, especially if you're not getting nvidia gtx 400 cards.
and i will say what i say to everyone building a new gaming comp: try squeeze an ssd into your budget! they are totally worth it, i would recommend them almost every time. if you must, just get a 5850 as it handles most games except crysis and those other often quoted games at max setting. they overclock like champs too, often as fast as 5870's at stock. the extra money from only getting a 5850 can be used to fund your ssd ^_^
Knowing absolutely nothing about SSD's, what size would you think I'd need? What is the primary purpose of having one? Is it so Windows loads faster or what? Oh, and will I need a controller card for it, or will it work with my motherboard?
After doing a little research, Ive decided to take your advice (thanks ItouchedYou) and add a SSD to my build. I selected an OCZ Vertex Series OCZSSD2-1VTX60G 2.5" 60GB SATA II MLC Internal Solid State Drive (SSD). The reviews I've read about it say it is one of the fastest SSD's you can buy. At $129 with a $20 rebate I could not pass it up. I kept the 5870 as well. 60GB sould be enough space for Windows 7, World of Warcraft and Final Fantasy XIV when it comes out. I canot wait till I get this bad boy together and see how it runs. Thanks for all your help.