Upgraded graphics now wont boot

[kevron2020]

I have had ubuntu for awhile and upgraded from 9.10 to 10.04 the day it was released, had 0 issues with 10.04 until I upgraded my graphics card in this comp. I went from a Geforce 5150 GS to a 7900GT now It wont boot into desktop (sorry still winblows brained, and am working on it) It boots to desktop:~$ How do I update my graphics from here. I assume it is cause of my upgrade cause it worked fine until I put this new card in.

If you need more info on my system just let me know..

Thank you