$1200 should do you fine but there are a few questions to help us help you:
1. Do you want a motherboard with or without SLi?
2. Do you plan on using the power supply that you have with that case? If so, what make and how many watts? If you need to purchase a PSU, forget these questions.
3. Will you be doing any overclocking?
Here are some tips:
a. Don't go cheap on the PSU because it is the backbone of a PC. For a gaming rig to play the games you want to play you need a good power supply. Personally I wouldn't go less than 500 watts. You also need to keep in mind that the PSU needs to supply a minimum of 30A on the 12v rail.
b. 1 Gig of RAM will do you, but you may want to consider 2 Gigs.
c. High grapics cards are big $. But they certainly deliver. Check out the TONS of posts on graphic cards and that should give you a good idea.
d. DVD drives that have good reps are LG, Lite-On, and NEC.
e. If you are not overclocking then Value RAM is the way to go. Crucial, Corsair, Patriot, etc. are a few of the names.