Windows 7 - Windows Backup

This may be a really stupid question, but what does a Windows Backup... back up?

Does it just back up files with certain extentions (e.g. documents, music files, pictures and viedo) or does it back up stuff like program configurations, programs as a whole, etc.

Here's why I ask, I was thinking about putting a new drive in my computer. Doing a clean Windows 7 install and then "recovering" a backup onto it from the old drive. I'm hoping to just "recover" documents, music, pictures and movies.

Thanks,
Eamon

Take look at this:

Windows Easy Transfer - Transfer To & From Computers

Backup Complete Computer - Create an Image Backup
System Image Recovery
Backup User and System Files

If you just want to transfer your own files (pics, docs, video, etc.), do yourself a favor and copy them youself to a stick or external disk. With the Windows backup you are liable not to be able to reimport them. Has happened many times.