You need a boot.ini file
Search and see if you have one.
If not you'll never boot to XP.
Did you tell the PC you were loading a 2nd O/S when you loaded the 2nd O/S?
There is a work around - you need to create a 'hidden' partition at the beginning of your C: drive which contains the boot file - but I am not 100% sure how to create one from scratch.