Disconnect everything except your hard drive.
That means floppy, cd, any modem, network card, video card(if you have onboard video use that, otherwise you'll ahve to leave that one).
Go into BIOS and load failsafe settings.
Put your Harddrive from your old computer in and boot off of it.
Hopefully it boots and runs fine. If it is extremely slow too then it is something on the mainboard.
Connect all devices back up, might want to do it one by one to see if one of them is the problem.
If this all works then you will know the problem is either a bad hard drive, or something bad going on on that harddrive. So at this point you would want to repartition, format and do a clean install on your old HD. And if it's still like that then your harddrive is toast, so just buy a new one.
