Laggy system...

[Bunnyman]

Hello, I've been havin a problem with games recently where they incure a major slowdown in performence, example: old game Guild wars, released in 2005 was gettin 75+ fps before now it's 20-30

Several games like mass effect, left 4 dead, fallout 3 were all goin great now they all have this lag/slowdown effect and idk what the problem could be, i've tried all sorts of things.

Firstly I thought the cpu could be the problem and I tested the cpu in 3dmark prior to the system goin fubar and got the same score as it is now, so that ain't it. memory is good, bought the same power supply as my bro who runs a superior system and still the same lag, so it ain't the power supply. reinstalled Windows XP sp3 and nothing, it can only be the graphics card but i've updated them to the latest drivers and tried older drivers to no avail.

I'm gettin a new rig but I really wanted to solve this problem, or give the comp to someone else at least.

It all started when I installed GTA IV (was never goin to play it on this rig just try it out) then noticed pretty low fps which was expected so closed it down and tried some other games then the low fps began, thought it might be securom so uninstalled both that and gta IV but still nothing.

here's the specs

Intel(R) Pentium(R) Dual Cpu E2180 @2.00ghz @1.99ghz
2.gb ram
XP sp3
NVIDIA Geforce 7900gtx 512mb


Although the system is sucky it did run modern games pretty well but now they all fail, i'm not exactly the best as far as problem solving goes so does anyone have any ideas what could be causing this slowdown ?