Hi there,
I'm just starting with linux and although all my precautions it didn't go as I planned.
I have 2 hard drives with the following configuration.
HD0(1) NTFS partition (active) with Windows XP (previously installed) - 12GB
HD0(2) FAT32 partition with user data (windows application and documents) - 28GB
HD1(1) NTFS backup of HD0(2) - 65 GB
HD1(2) Linux boot partition (active) - 102MB
HD1(3) Linux data partition fedora recently installed
HD1(4) Linux swap partition - 508MB

This is what i wanted:
I'd like to have the 2 OS completely separated using BIOS boot sequence to switch between them so that booting from HD0 would come windows (no boot menu) and booting from HD1 would come Linux (no boot menu).

During fedora installation I installed GRUB and specifically said no to use windows HD.

This is what happened:
GRUB changed the MBR in HD0 (windows), so when I choose to boot from it in BIOS, I get a boot menu with both windows and linux working.
On the other hand, if I tell BIOS to boot directly from linux HD I get an error and no OS starts: Error when loading the operational system absent Operational system

What I need to do:
Remove grub from windows HD MBR so it can boot even if the other HD is absent. **My windows XP CD does not boot.**
Configure GRUB on linux HD MBR.

Can anyone halp me?

The way to remove a bootloader is to over-write it with another.
To do this you will have to boot the XP CD, and run "fixmbr" from the recovery centre.

Re-installing grub to the second disk is pretty trivial, but won't help you much until you can sort out the primary disk.