Graphics Crash

I recently tried to upgrade my Radeon 7500 64Meg graphics
card to a 9200SE 128Meg card, but being rather
temperamental, my PC didnt like it. So, i removed the new
software and card, and tried to revert to the old card-
also didnt like it. My system can run under W98 safe
mode, but other than that the screen garbles trying to
load windows. Any ideas? I tried re-installing windows,
but it wouldnt let me because of disk-compression
programs I have. I also tried re-installing the drivers
for the original graphics card, but in order to complete
the process I have to restart, which of course crashes my
system.