HELP!! ingame lag in portal

[foobby]

im laging ALOT in portal's menu and in game.
other source games seem to run fine and smoothe (somtimes teamfortress 2 lag for 5-10 sec in the menu at the start)(not sure about half life 2 ep 2)
any segestion???


MB: EVGA 122-CK-NF68-T1 N680i SLI 1
VGA: EVGA 512-P3-N802-AR 8800GT 512M 1
CPU: INTEL|C2Q Q6600 2.40G 775 8M R 1
PSU: ROSEWILL|RP550 RETAIL 1
MEM: 1Gx2|OCZ DII800 OCZ2P8002GK R 1
HD: 320G|WD 7K 8M SATA2 WD3200AAJS % 1
DVD: BURN ASUS|DRW-2014L1T LS SATA
CASE: RAIDMAX|ATX-612WB BK RT
i got windows xp (crack)

 

[worshipme]

Valve's games always take a few seconds to load the background image with the menu, but you say you get lag in game as well?

 

[foobby]

Valve's games always take a few seconds to load the background image with the menu, but you say you get lag in game as well?

well i no that it takes time to load the image, but after its done loading, it lags uncontrolably, i sometimes cant quit, and have to use atl ctrl del to get out. yes if i some how able to start a game the loading screen is fast and quick but wen im IN the game it lags just like the menu