Windows won't reinstall.

Ok I know I have never had a problem reinstalling windows before. Now
with a new AMD processor and motherboar I cannot reinstall windows XP
at all. It simply restarts the computer 10 seconds after I hit enter
or "r". There's no liscense agreement. i can get into safe mode and
such but it doesn't boot up normally. I know that's not supposed to
happen. i don't know what to do. COmp usa said after they installed
everything with the new motherboard that I would just have to reinstall
windows. "That's simple" i said.


10 hours later I'm stuck perplexed and frustrated.

.