I wanted to try out my geforce 2 MX400 PCI video card in my dads computer which has an TNT2 AGP card in it already. before i put the PCI card in, i changed the setting "primary video adapter" in the BIOS from AGP to PCI. when i put the PCI card in and plugged the monitor it works up to when the user welcome screen. the user welcome screen just doesnt display, neither does the mouse pointer then i switched the computer off, and then on again and changed the setting in the BIOS back to AGP, and plugged the monitor into the TNT2 again as before i started. i switched it on and now the welcome screen does not start aswell. now i cant get into the computer, the screen just remains black and nothing happens. what have i done??? i cant even reinstall windows or format the hard drive because when i boot from cd, it works fine until it says "searching for previous versions of windows" it just stops. the main problem is that it just stops all the time. after the loading windows screen it just stops, when i try safe mode, the white text which says C:windows\system....etc all over the screen just remains and it stops. what am i going to do is it possible to take out his hard drive and put it into my computer, then somehow back up the files which are important from it? what can i do? i need help!!!

The first thing you need to do is calm down. You probably didn't break anything. Install the AGP card and take time to check that EVERYTHING is seated firmly into their slots. Check the Ram and all the wires too. Now look at the video cable to make sure it didn't loose any pins. Sometimes you will get a small static charge built-up in the video cable, so rub the cable on your hand to discharge and residual charge. Plug everything in and power the unit up. If it fails to load completely; DO IT AGAIN! If it worked before – it will work again!