1) Are you booting to an oririnal XP Home or Professional CD?
2) When you exit bios, are you saving your settings? Next time you go in make sure CD is still at the top of the list.
3) How many CD drives do you have?
Hi, I see its not working too well for you. I do not endorse illegal copying, but I will not judge you for it either. Perhaps you even have a legal copy of WinXP. If you copy a bootable CD by placing the files on your harddisk and THEN copying those to a new CD, or, if you copy the CD by selecting the files on it and THEN copying those to a new CD, the result will be a NON bootable CD. You must do 1:1 CD copies to retain CD bootability.
If you are sure your WinXP CD is fine (bootable or not) you may want to consider using a bootflop and doing an installation from there. Again... they have some nice WinXP bootflops from the site i mentioned earlier.
Ofcoarse, making you current CD bootable is great, but a bit more work.