unplug all the HDD's, set DVD as first boot device, and boot. see if it will boot from it then.
If not even then..something in your BIOS or the disk itself is fubar'd ID say..
And i THINK you can start a windows install from windows with the disk. Just start it from my computer. Windows 7 I know you can, I haven't touched XP is so long, I cant remember...but I seem to be leaning towards I remember you could.
It will start up, copy the files it needs to do the install and reboot and finish.
-We don't control what happens to us in life, but we control how we respond to what happens in life.
-Hard times create strong men, strong men create good times, good times create weak men, and weak men create hard times. -G. Michael Hopf
Disclaimer: Post made by me are of my own creation. A delusional mind relayed in text form.