So your install of fedora on your winsxp machine never altered MBR?
If so you can still boot xp without problems?
Can you share the "grup" screen capture installation procedure ?
Once I let Fedora automatically partition it just installed grub & said it was done.
It never did ask where to install grub.
The only thing I did was modify grub so that it would show the boot menu. That was the bug I had.