Compaq Presario Can Only Boot From Hard Disk

Compaq presario with Vista. Trying to do a clean install of windows 7 on comapq presario f500. Problem is the machine will only boot from hard drive. Cd drive works fine just can't boot from it. Windows 7 install disk won't boot. Windows xp install cd won't boot. In bios setup I've move the dvd/cdrom drive to top of boot list still no luck. So I got tricky booted from vista and starting windows 7 install cd from windows explorer. Install hung part way through and I had to turn off the computer. No I can't boot vista and have an incomplete install of windows 7 which won't boot. Not even safe mode. When you boot hit Esc the boot menus only shows notebook hard drive as an option. I've also tried unpluging the battery to clear out.