No display and beeps after changing videocard

Hi,
I am kinda new to hardware issues, so I found this website.

I have here some old computer, with an old 64mb GeForce. I replaced that one with a slightly newer one (128mb GeForce MX 440). I started the computer, installed the new video driver, witout uninstalling the other one. After this I needed to boot but the computer won't start properly, and by this I mean that I have no signal coming to the monitor, and I hear a series of beeps. As far as I know, those beeps indicate what's the matter, if the computer doesn't start. I get one long beep, pause, eight short, pause, one short, pause, two short, pause, one short. Everything else seems to work: hdd, source motherboard etc.
I inserted the previous video card back, but I get exactly the same result.

What could be the problem? Is it that I haven't uninstalled the previous driver?

I really don't think that this is part of my problem, but the GeForce MX440 card had a pin stuck in its female VGA connector before, that I managed to pull out.

Please help!!