going forever in restart loop.

I set up a network the other day there. worked fine everything was great. moved all the stuff from my old computer to the new one. I am giving the old one to my dad so we can play network games. so I thought I would clean the old one out by using the reload disk that came with it. used it before to fix the computer no problems.

well this time no luck, when I used it it says there is a virus in BOOT sector continue y/n. I said no, then virus scanned but nothing found. I put my reload disk back in and same message so I went ahead. everything went fine intill I wanted to update the computer. after I downloaded the updates not even SP2 yet. it asks to be restart. so I restart and now it just goes in a loop of restarts. Safe mode does turn up, but I tried getting rid of the updatews but that does not work. a virus scan in safe mode brings up errors in the boot and partion drive (SP).

I tried the reload disk again same thing as I said in the top, boot sector virus.
I think that is everything If I missed anything please ask?
how do I stop this? how do I make it stable enough