Do you want to uninstall Linux? (Why? ¿? )
I guess that the backup partition has a win$hit filesystem, am i right?
1) Use a program like: QtParted http://www.icewalkers.com/Linux/Soft.../QtParted.html
You´ve 2 partitions, so:
# Format the linux partition to NTFS/FAT
# Or If you want to keep linux, and have free space on the backup partition, make some room for win$hit there(create a new partition).
2)Put the WinXP cd and install it again, or reinstall it, whatever.
This will take care of the MBR.
Now you´re set,
If you didn´t deleted the linux partition, then:
Put the Fedora cd there and type: linux rescue (or something like that)