Help In Playing Games

[That_One_Foo]

when i play rise of nations first the games starts getting slower then theres black and green colors fluttering in the background then it freezes and i have no other choice but to restart and when i play battle field 2 theres just fluttering colors in the background and its pretty slow i don't know how to fix this i hope some one can help me

My SPEC ARE:
AMD athlon x2 4600
1x 512 mb of ram
GeForce 7900 gs with the latest drivers
1x 500 gb hard drive
msi k9n4 sli motherboard
500 wat thermaltake power supply

p.s.
also when starting the computer up the screens aren't aligned

 

[Adhmuz]

that sounds like an obvious graphics card issue, could possibly be defective or theres a driver conflict or some other conflict with your monitor, quickly try re-installing your video drivers. If that doesn't solve anything try contacting the manufacturer.