GTS 450 1 GB

I replaced my broken 9800 GT with GTS 450 1 GB, and i try to play Napoleon, but game run worse than with 9800GT. I try other games and all runs worse than with 9800 GT. I don`t know what to do.
I install fresh copy of windows and updated my drivers but same.
I try to set Power Managment mode in Prefer maximum performance but same.
My comp
Amd x2 5400+
2 gb of ram
PSU 460 W

Help!

I solve problem, i install older driver, i got these drivers with graphic card.
But i think that new drivers are better than old, weird.

Fresh install of Windows = did you reinstall the motherboard chipset drivers for your OS?

Nope i just format C partition and install windows, how to reinstall the motherboard chipset drivers?

EDIT: I again try new drivers 267.59, but now i set my Nvidia settings in control panel to default, and now works great.

Do you have your motherboard install disc?

Have you searched your motherboard's website?

Yes i have motherboard disc, and i install drivers.
THX now all system works better.

You're welcome.