latitude d620 video issue

Hi

At the first place please excuse my English, I'm not a native.

I've got following problem with my latitude D620 (with intel GMA 945)

I reinstalled OS (win XP pro) and installed all recommended drivers from dell official site (latest versions). But it seems the video driver doesn't working.

In the Device Manager is everything OK (no yellow  exclamation marks) but 3D performance is horrible.

When I reinstalled video driver (no mater what version - it doesn't change anything) and reboot ntb, everything seemed to be OK (1st 3d application I tried (DirectX game) run fluently), but when I quit this application and run another (or even the same one), it runs horrible again.

I tried various versions of VGA drivers, reinstall OS, I even tried another version of OS (win 7 - I tried it will have found good drivers itself) - but nothing helped.

Before OS reinstall I didn't have this problem...

I'm starting to be desperate...

Please Anyone, help me!

Thx