Best Available Gaming System

Hey guys I don't know much about computers however I am looking at buying a gaming desktop. Im looking for something that will last me as long as possible before having to upgrade again.

APPROXIMATE PURCHASE DATE: ASAP

BUDGET RANGE: $700 After Rebates

SYSTEM USAGE FROM MOST TO LEAST IMPORTANT: Pure Gaming

PARTS NOT REQUIRED: Mouse, Keyboard, Hard Drive, Monitor, SoundCard, dvd drive, Video Card (Ill talk about this later)

PREFERRED WEBSITE(S) FOR PARTS: I live in California so Newegg is probably the best. Or i live next to a Fry's Electronics if that is better.

PARTS PREFERENCES: Intel CPU, I would like the motherboard upgradeable to new things that come out if possible.

OVERCLOCKING: Yes

MONITOR RESOLUTION: 1440 x 900. Its a Samsung SyncMaster 906BW

ADDITIONAL COMMENTS: The main reason I am buying a new desktop is because I have a gaming laptop but it isn't able to play the games that are coming out. I have 2 video cards and I know they can play the games now and I will upgrade them when I need to so that's why I dont need to buy a video card yet. Probably when I can't play a game.

My 2 video cards I have are a NVIDIA 7900GT (oc) and an ATI RADEON x1950xtx. I know they are pretty old but for now they can play the games I want to play and when I buy a game that can't run it ill upgrade then. I just don't know which one is better so if someone could tell me which one to use that would be great. I appreciate any input! Thanks!

i guess if you could show me a build for with a video card and without a video card that would be good. Which video card is better between the two though?