Help with Black Planes in games

[Dante13]

I just bought a new 6600LE Evga. And I keep getting weird textures. Where black shapes will surround most of the screen. I can barely see in some games. I need help with this. Please and thanks. BTW, this is what I'm running
P4 2.5ghz
160GB HD
512 RAM
EVGA 6600LE 256MB
Mobo: L4S5MG+- SIS651 chipset
Socket 478
PSU 330watts