Cant install windows 7 on new hard drive

Watch the CD drive light next time you boot. Does the CD light start to flash and the drive spin up? If not, you probably need to change your drive boot order. When your computer starts up, it should tell you that you can press a key for the boot menu - usually a function key like F12 or F9. It will depend on your BIOS. It flashes pretty quickly on most computers, so you may need to try a couple times. If you don't see anything like that when you boot, then you will need to access the BIOS and change the boot order there.

I can't say for sure, but it sounds like maybe your hard drive is set as the first boot device. Now once you set the CD drive as the primary boot device or choose it from the boot menu, make sure you watch the screen. The Windows boot disk will prompt you to press Any Key to boot from the CD. If you don't, it will go right back to trying to start from the hard drive.