$750 gaming computer; first time builder

Hello all, I was interested in getting the $750 gaming system from the system builder marathon, march 2010. The reviews showed it’s a solid computer. im not tech savvy and have struggled finding everything, especially information regarding why certain video cards or motherboards are better than others. this will be my first computer I build and it will be used for gaming, mainly starcraft 2, lord of the rings online and Diablo 3. i have a few concerns I haven’t answered and was hoping the community could answer my questions.

APPROXIMATE PURCHASE DATE: as soon as possible

BUDGET RANGE: $1000

SYSTEM USAGE FROM MOST TO LEAST IMPORTANT: gaming (starcraft 2, lord of the rings online, Diablo 3), research

PARTS NOT REQUIRED: keyboard, mouse, speakers, OS

PREFERRED WEBSITE(S) FOR PARTS: newegg, tigerdirect, anything legit

PARTS PREFERENCES: I read the system builder marathon march 2010 $750 gaming desktop. Was interested in this build
Power Supply: Antec EarthWatts EA650 650W http://www.newegg.com/Product/Product.aspx?cm_mmc=Tomsh...
Case: Antec Three Hundred Illusion http://www.newegg.com/Product/Product.aspx?cm_mmc=Tomsh...
Motherboard: Gigabyte GA-MA790GPT-UD3H http://www.newegg.com/Product/Product.aspx?cm_mmc=Tomsh...
Processor: AMD Athlon II X3 435 http://www.newegg.com/Product/Product.aspx?cm_mmc=Tomsh...
CPU Cooler: Xigmatek HDT-SD964 http://www.newegg.com/Product/Product.aspx?cm_mmc=Tomsh...
Graphics Card: Two Sapphire 100245HDMI Radeon HD 4850 512MB http://www.newegg.com/Product/Product.aspx?cm_mmc=Tomsh...
Memory: G.Skill F3-12800L9D-4GBRL x 2, 4GB http://www.newegg.com/Product/Product.aspx?cm_mmc=Tomsh...
Monitor: Hanns•G HW-191APB Black 19" 5ms Widescreen LCD Monitor http://www.newegg.com/Product/Product.aspx?Item=N82E168...
Hard Drive: Western Digital Caviar Black WD6401AALS http://www.newegg.com/Product/Product.aspx?cm_mmc=Tomsh...
CD/DVD drive: LG Black 22X DVD Burner SATA Model GH22NS50 http://www.newegg.com/Product/Product.aspx?cm_mmc=Tomsh...

OVERCLOCKING: if necessary

SLI OR CROSSFIRE: crossfire

MONITOR RESOLUTION: not sure. Something reasonable in the monitor I pasted

ADDITIONAL COMMENTS:
My questions are this:
Is this computer overkill for those games? I’d like to play them in the highest settings possible, but in a heated multiplayer competition, it might not be feasible running ultra settings so im willing to settle. Again, I tried researching what cards would do what, but it was hard to find something I could put together. I see charts with lots of numbers on them, but I can’t find anything reliably explaining the cards’ history.

Im not interested in a 640GB hd. Is there something I could get that would carry half that much? I don’t expect taking that much room. I looked for other harddrives but others for 300GB are for notebooks or no longer in production. Am I stuck getting something large?

The graphics cards can’t support directx 11. Is that going to be a problem, say, 2 years down the road, or is the technology used in this computer meant to last this year and be replaced so quickly?

The optical drive reviews say it has spyware but can be removed. Any thoughts?

I know it’s a lot of questions and im sorry if it seems like im pawning my research to you guys. If you show me something readable I’ll check it out. Thanks SO MUCH For your time!