Do you close all unnecessary processes prior to gaming. I use a tool called enditall. It kills a bunch of processes giving you more memory to play with. It may not e your video that's slowing you down. Also check your PC for spyware & adware. See links below.

http://www.safer-networking.org/en/download/


http://www.pcmag.com/article2/0%2C4149%2C697%2C00.asp





Dim 4400
P4 2.84G (upgrade from 1.7)
1024 mb PC 2100
BFG Geforce 6600GT OC AGP>so sweeeeet!
40G WD HDD (Windows XP SP2)
45G WD HDD
SB Live!
CDRW
DVD
21" Panasonic E110 CRT

More ram will also help you with HL2, make sure got the latest video drivers

Dim 4550
P4 2.4G 533
1024Mb DDR@333Mhz
Maxtor 30GB 7200rpm
Maxtor 120GB 7200rpm
NVIDIA TI 4200 64MB
SB Live with 5.1
Plextor PX-708A DVD +/- R/RW
HL-DT-ST CD-RW Drive
Samsung 193P
XP Home SP2

Agree, A gig of ram helps with the new games (HL2, Doom III, MOHPA etc.). Ram utilization tools show even over a gig is utilized at points in these games.

I experienced the same problem with Half-Life 2 it lagged quite a lot, but when I upgraded to 1gigabyte of ram the game stopped lagging.