installed graphics card and forgot to delete old drivers!!

[avalanche]

I installed a newer graphics card given to me by a friend, it is an agp card and should work in my computer.  I rushed it into my computer and of course without reading the directions<won't do that again> upon restarting my computer the compaq sign appeared but nothing else would work, harddrive spins fans spin but no boot up sounds.  I tried putting my old one back in and I couldn't even get the compaq intro screen to come up, I tried restarting my computer a few times only to have it restart on me after starting it up each time.  I then tried to plug my screen into the motherboard graphics port to see if my graphics cards were messed up only to have the same issue with that, nothing on my screen.  When I unplug my screens cord it comes on telling me I have no signal, but when I plug it back in it just goes blank again.  A buddy who know more than I do says that my drivers are messed up but I can't even access anything without of course the computer booting up so I can delete the old ones.  HELP ME!!! I don't want to buy another computer (can't afford it right now).  I have a laptop that I am using right now so I can find out information on this stuff but nothing has helped me so far......

[Jonas Wauters]

Did you try resetting your mobo?
Unplug your computer for 15 seconds that replug and boot.
Does that help?
I don't quite get your problem:
So you can get past the BIOS but you can't load your OS?
What OS are you using?
Did you tried going into safe mode?

Jonas