I'm not an expert on imaging but here's what I know. The system imaging tool that comes with Windows 7 is very basic. By that I mean it will make an image of everything on your hard drive. I've heard people say there are ways to select only certain drives or partitions but the failure rate is high. Also, the Windows 7 imaging tool doesn't like making images to DVDs even though that's one of the options.
Once you make your image with Windows 7 you have to use a special System Repair Disc in order to access that image. At the end of the imaging process you'll get a prompt "Do you want to create a system repair disc?" (See Step 9 in the tutorial.) You need to create that repair disc on a separate CD and that's the CD you'd use to boot your computer if you ever need to use the image.
If you want a better way to image your computer and be able to select or unselect different drives or partitions, there's a couple of free imaging tools that many people on this forum recommend. One is Macrium Reflect free and the other is Paragon. They will both allow you much more control over what is or isn't imaged. One of the forum members made a nice tutorial for Macrium here
. And this is where you can find out more about free Paragon
. (If you decide to use either Macrium or Paragon, they will also require that you create a repair disc so you can boot your computer and access their system image.) Hope this helps.