Incorrect. F8 is to get to the boot options menu of an installed XP system.
The OP can obviously enter BIOS setup as he has stated "changed boot order."
@mrmstolp,
Try poking the F12 key during boot. Some BIOS versions support a boot-choice from pressing F12 at startup.
Some systems, especially older computers, could not boot from CD. Hopefully yours is Boot-CD capable. There may also be IDE port capability issues in BIOS preventing booting from CD.
Give your make & model and some checking will be done to examine possibilities.