Sounds like you are booting to the disc again after the initial install, you don't want this. When the machine reboots the first time after the initial install/copy of files, press the eject button on your cd/dvd drive and take it out. The system should then boot to the hard drive you just copied your installation files to and continue.
Alternatively you could set your bios boot order to boot to your hard drive FIRST, and then use whatever your BIOS hotkey is to select the DVD/CD drive from the on-the-fly boot menu the first time. This will boot to your Windows 7 DVD for the install, when it reboots it'll hit the hard drive first and continue on.