motherboard help please

My system is screwed up bad--i have a asus a8n sli board w/XP. i had a virus on HD and was removing it--i went to reboot and saw blue screen death. I kept messing with it for a couple days but no luck. I tried windows repair,new format--nothing. I can get to the post screen and it beeps 1 time short and i can get into the bios mode for bios settings and after i exit bios settings it just hangs at the pci device listing page where it shows cpu clock speed,HDs,memory,cache until i hit Ctrl-alt-del and it does it again.i even tried putting another HD from other computer and it does same thing--does not boot.i can't even get in F8 for safe mode.I get a disk boot failure--insert system disk disk and press enter----any suggestions??