NO BOOT PARTITION

The computer, a Dell Inspiron 6000 with Windows XP will not boot up. The partition has been changed with Partition Magic (tragic!), I need to run FIXMBR, FIXBOOT, and copy NTLDR and NTDETECT.COM to the root. In the Windows Recovery window, the drive does not show, but I can access it in DOS with a Linux CD. I cannot run FIXMBR etc in dos, so how do I fix this to boot? It does show in windows explorer, but I cannot fix it in Windows.