I've installed BeOS5 PE onto a 1gig partition on my Celeron. It's working fine, but I'd rather dual boot with WinXP in a different way, but I cannot seem to be able to uninstall the BeOS bootloader. I've looked for a boot.ini and the only one I find doesn't seem to mention BeOS, but yet I get the selection every time I boot.
I was going to try fdisk/mbr, but I thought I'd better ask you all first. Thanks

If you haven't tried it then yes fdisk can replace the mbr along with a number of other apps. BE SURE to make a copy before you do that though!!!!! Use ranish to save a copy. The reason is that some installs might be rather goofy. Like mine is. You might need to have some of the mbr data to manually edit to repair easily xp.

you can also try this:

Boot from the Windows XP CD, press the key "R" in the setup in order to start the restoration console. Select your Windows XP installation from the list, and enter the administrator password. Enter the command "FIXMBR" at the input prompt and confirm the next question with "y". Finally, use "exit" to restore the computer.