Jumpy Performance

Ok, february second i became a proud owner of my Inspiron 5150, but last week, i noticed a ugly side to it, and it occours to a friend of mine as well, heres the problem.

In the following Games...

Counter-Strike (on Direct3D Mode and Software)

Need For Speed : Underground

The Elder Scrolls 3 : Morrowind

Raven Shield

Quake 1

I get a strange jump in performance, for example, in counterstrike, i check how many Frames Per Second i get, its always at a constant 71 (60 if at 1600x1200) but when i turn it on Direct3D mode things start to get grim, i get weird Performance jumps, if i leave Speedstep enabled on in the BIOS, then it goes in slow motion every now and then, making it unplayable, if i disable Speedstep, then it speeds up so fast i dont know whats going on.

In Ravenshield i get the same problem, only its constantly happenning, and is unplayable

Need For Speed : Underground, slows down everynow and then, completely ruins the game

Quake 1, everytime the weapon bobs it slows down then speeds up, its terrible against bots in OpenGL

Morrowind, poor mouse response, if i move the mouse, it responds a second later, or slightly faster.

all of these games i play at their highest settings, except Morrowind because anyone who has played it on its minimum required computer would know what i mean.

my nVidia driver version is  6.14.10.4585, the latest ones from Dell

im thinking of getting the drivers modded, and see what happens, because im on the edge of formatting again.

oh, and my laptop specs

Pentium 4 with HyperThreading 3.06ghz

512mb DDR SD RAM

40gig hd (37gig  really)

Geforce FX 5200 GO 64mb AGP 4x

UXGA screen, forgot measurements, but it goes up to 1600x1200

DVD Burner, + r dvds only.