Sounds like its still trying to boot to the failed install, not the CD/DVD drive.
Either look at the bottom of the boot screen and look for BOOT ORDER press key blah blah. Then pick the CD/DVD. Or go into the bios and set the CD/DVD drive as first in the boot order.
i did and selected f12 and hit cd/dvd drive. then i hit any key to boot from dvd drive and it gives me this
http://s15.photobucket.com/user/The_Volcano/media/CAM00204.jpg.html
if i chainge the bios though f2 and select cd dvd drive to boot first it gives me this
http://s15.photobucket.com/user/The_Volcano/media/CAM00205.jpg.html
says could not find BOOTMGR is missing. i dont have issues with this on my xps 1640. this is a dell oem disc. i got the windows 8 disk to work one time and it gave me an error that the cd/dvd drive is missing and asked me to locate it. i no longer want windows 7 or windows 8 on this machine if it cant handel a fresh install. i just want to a way to get xp back on this computer.
i am going to try windows xp disk when i can get it. will get back to you guys. this is what i figured the parts in the computer are just old.