knoppix and ms nt server plz reply asap

hi
ive booted knoppix on a computer, but know i want to boot ms nt server on the computer. i installed it, and then it tells me to restart it to finish installation. but then it boots up knoppix from cd even though the cd's not in there. so it goes wrong and doesnt boot up linux or nt server. so ive tried to do fdisk /mbr but that wont work and i tried fdisk/mbr but it wont work, how do i get rid of knoppix and carry on the nt server installation.
thanks Dan