Cannot Boot OS from CD

[tenner]

i have dualboot, Winxp and Suse 10 which work perfectly fine. However I want to reformat the partition Winxp is on and reinstall windows. Upon putting in the Winxp disc it will say Press Any Key to Boot From CD but it will just take me to the Suse menu that lets me choose between windows or suse. Any clues? I do not know for certain if Suse is on the same partition as Winxp, i cannot find any Suse system files when I'm in Winxp..
thanks for looking

p.s. also, how can i remove a partial Winxp install (where at the start up it says choose between Windows Xp Pro or Windows Xp Pro Setup)
thanks!