So, let me get this straight. You are trying to run 2 different machines now off of your two seperate hd's? If so, then your problem really isnt all that bad. Seperate the Hd's and put them into the respective boxes. Then, reinsert your XP disk and reinstall xp over itself. You should not lose any data by doing this but if you dont have any backups, its your fault.
Now, Take out your Red hat 7.3 disks and boot from the disk. Select recover and customize your install. Then simply deselect everything. So, you should be good after that.

10ded