Video Problem, hoping for help vostro1700

Hi, well i'am actually having some problems video-related, and i tried a bunch of things but none have given me any result, anyway im posting here what if 've done, and maybe someone can help me.
I have a vostro 1700 w/ intel T8100 / 3gb ram/ 8600m gt/ dual hdd 160gb

I have some games like DMC4, PURE, Far cry 2, and i was playing them several times a week. UNTIL, the other day, i installed GTA4.
It run at 22fps.. and i was like crap, so i looked the forums and everyone was mad cause it's freaking stupid how hard it is to get the game run well.
OK, i go to sleep.
Next morning... gta4, 5fps. i say !? then i try PURE, i get some kind of stuttering, but heavier....i can't even run the game well.
i try DMC4, it runs really weird, like in the in-game vids, i get the feeling it is running really low. In-game playing, it run's barely OK.
but it was not, what it used to be.

So i freak out... i unistalled gta4, i removed all programs that came with it.... but everything is the same, i can't get no fix.
Even, when windows XP starts, before the LOGO bar starts to load, you get a FADE between the blank screen, and the logo one. Well, that fade takes a long time, until the bar starts to load.

Then, if i am with NERO BURNING ROM opened, and i insert a blank cd/dvd, my system hang's for a sec, and then comes back, like if nothing happened.

I also have problems viewing video-streaming by web browers (i see them with really low fps), but no problems viewing a dvd.

Maybe, i have just another defective 8600m gt, but... the thing is i have never got overheat on the board.. i never goes beyond 75º... even with intense gaming after several hours.

I also run a memtest86 to see if it was the ram, but it went ok (another weird thing, memtest86 and gta4 recognized my intel c2d as a "intel pentium III xenon")

Maybe someone can give me a hand... uaaaaa

 

Try formatting your hard drive and reinstalling Windows. It seems to me like GTA4 messed with some sort of system settings that are hard as hell to change back.

 

yeah, that was my thought... but, is that really possible? i mean... it's just a fkng game...