Windows 7 (and BIOS) don't detect new hard drive

Hello everyone. Not sure if this belongs here or in the hardware forum, but here goes.

The hard drive in my Dell XPS 1640 laptop failed, and so i bought a new one and was planning to do a fresh install of Windows 7. What I thought was, I'd take out the old hard drive, put in the new one, and install Windows 7 off a USB stick.

Removing the old and installing the new went as expected, but when trying to install Windows, no drives were found. I went back into the BIOS and saw that the new drive isn't being detected. Was there another step I needed to take? I assumed I just install the new hard drive just the way the old one was installed, same screws, same connector, etc., and it would work. Apparently I was wrong. Can anyone help? It must be something very basic and obvious that I'm doing wrong.

Thanks.

Ah, yes, that does seem relevant. OK, what came out was a Seagate Momentus 7200.4 500GB. What went in was a Western Digital Scorpio Black 750 GB.

Try reinstalling the HD until it registers in BIOS. The contacts may need cleaning of dust or not be fully engaged.

Yes, thanks. There was a little connector I hadn't pushed all the way in. Now it's working. Thank you!

Good news. Follow these steps to get a perfect Clean Reinstall - Factory OEM Windows 7