First Computer ever for Gaming budget 1000 maybe +

Hello,

Intro:
I am looking into building my first Computer that will be used for gaming. I have done some research over the past month but I am still confused and need guidence and help/Ideas.

Why:
I really want to experience how to build a computer and seeing all that goes into it and better understand how they operate. (Even if it means going slightly over the 1000 dollar budget)

Timetable:
would love to start building it Immediatly and have it ready ASAP, but there is no life or death consequence by waiting some more! : )

THE LIST
Case:
Antec Nine Hundred Steel ATX Ultimate Gamer PC Case (Black)
(have)

Processor:
Intel Core 2 Duo E8400 3.0 GHz 6M L2 Cache 1333MHz FSB LGA775 Dual-Core Processor
(Good enough for high but not extreme gaming?)

Power:
Corsair CMPSU-650TX 650-Watt TX Series 80 Plus Certified Power Supply compatible with Intel Core i7 and Core i5
(Only for Core I7 and I5?)

Motherboard:
(Uncertain)

Hardrive:
(Uncertain)

Accessories-Mouse, keyboard, and screen:
(I'll easily take care of)

Things I missed:
(Alot)

Any input would be greatly appreciated

Thanks!

Need to know size and native resolution of the screen you intend to use.

Will give some input then, but at the end of the day will advise you to wait another week since Intel will be announcing new cpu's and the reviews are ready to be published.