There should be a jumper on the motherboard, probably close to the CMOS battery. Turn the computer off, turn off the rocker switch on the power supply, move the jumper to the clear position. I usually hit the power switch once while the jumper is on clear and the PSU is shut off, just to make sure it is drained.
This should reset the BIOS to factory default. A big problem with Nforcechipset motherboards is that this hasn't allways been enough.
But the more extreme measures were necessary only when the computer wouldn't even POST (just a black screen). Yours is at least POST'ing, so I think clearing CMOS will do the trick.
One question, before you tried to repair the NTLDR, did you change the boot order to boot from the CDROM first?