still trying to tweek my system

So after my reformat i have lost some major performance. With the same settings i am only getting 10 fps when i am used to 19-20. My system says my processor is only working at 797 Mhz when i have a normal peak of 1500. also, this i think i already have figured out, is my vid card. its not displaying correctly, in tower view in fs9 it shows some annoying black box things on the fusalage. I probly need to update but not fully shure on how to do this. I have a Nvidia Geforce4 420 Go 32m. where do i get the uptade drivers and how can i get more power out of my processor. help would be great.