One of the things I like to do with the computer is try out various programs. This often leads to using a Windows 7 disk image to return the computer to a clean state, perhaps as frequently as every few days. In fact, trials of software also includes various security programs. I'll take this opportunity to say that having used other security solutions for a while I came back to using the NIS 2010/Sandboxie layered combination because I think it good. Just a plug for Norton there.
Windows 7 disk imaging (found in 'Windows Backup and Restore') has proved easy to use and reliable. It has some limitations compared to other disk imaging solutions. For instance, images can't be explored and it doesn't do incremental back-ups. However, there is an option given to back up files before restoring the system with the disk image. Using this prevents files that were created since the image was made from being lost. The files can be written back to the system after the image has been used.
The restore operation can normally be started from within Windows. However, if ever this wasn't possible due to a drastic system fault, a boot disk can be used. Windows 7 Backup and Restore includes an option to make the disk. Once booted from that, the procedure then goes on to find the disk image necessary for restoring the system to a trouble-free state.
Perhaps worth a mention is one occasion I had where the computer would not start even with the boot disk. The software trialled had perhaps written something to disk that caused this. Maybe the first reason given here. Whilst there may have been another way, the solution was to reinstall the operating system just enough to allow access to a previously made disk image. Using this, it was possible to restore everything to a fully working up-to-date condition. Probably a rare circumstance that caused this problem. Only mentioned in order to show how the disk image can get the computer out of disastrous trouble without resorting to a complete reinstallation of the OS and programs.
By default, making a new disk image will overwrite any existing one it finds on a second disk or partition. However, it is possible to arrange a folder system that makes it possible to keep more than one image. A Windows disk image takes the form of a folder on the second drive. It has the name of 'WindowsImageBackup'. What has to be done is to move this folder into a new folder of its own so that later imaging operations do not find it. Then a second separate backup can be made with no danger of the existing image being overwritten. Put the new second image in a folder of its own too. Give both folders meaningful names as to what backups they contain.
So, it is possible to have a folder named (for instance) 'Windows Disk Images'. Inside this can be several folders bearing the names of backups. Inside each of these folders is a 'WindowsImageBackup' folder that contains the OS and programs at a particular stage or condition.
To restore from one of these, bring the required 'WindowsImageBackup' folder out and put it out on the root of the second disk where the imaging process can find it.
It might sound complicated to have multiple images but it isn't in practice and the method does work.
The above is based on my own way of using Windows disk images and experiences encountered. As always, mileages may vary but I hope what is written will be useful to anyone considering giving Windows 7 disk imaging a try.