I accidentally installed grub and couldn’t figure out how to uninstall or override it with another boot loader. The others just weren’t working. Running fdisk /mbr didn’t work for me either. What I had to do was insert and boot the XP CD, then go to the repair console and type fixmbr. I just rebooted and it went straight into DOS like it was supposed to.
If you get a “Sharing Violation” error while using the DOS “xcopy” program, just use the “/C” switch to make it continue copying even if errors occur.