I usually reformat my home PCs regularly after sometime but since it's time consuming I thought I could just restore an entire OS from a backup.
How do you usually take a "snapshot" of a fresh OS installation, save it to a DVD, then restore it later as if you've just reformatted?
You're looking for Disk Cloning utilities, such as Ghost. This is probably a good place to start: http://en.wikipedia.org/wiki/List_of_disk_cloning_software.
You're still going to format the drive though, but I assume that's desired, since you want to restore the drive to the state it was when the clone was made.
I prefer true fresh reinstalls. What I do for my personal systems is to set up a reference box, then make note of EVERY setting change. (Wallpaper, Control Panel Classic view, show hidden files, show file exensions, etc, etc...) Then write a simple batch or reg file to import all of those settings at once.
For software, Ninite. Man, that thing is a godsend. I really wish it didn't set up 7-zip to be the default .zip handler, but other than that, it's gold.
Isn't that a windows facility too? I did it myself on my Windows 7 using control panel.
Sometimes there is a hidden menu in your BIOS. THe OEMs make it available by using a specific combination key for example CTRL+F11 or CTRL+F6. You have to keep pressing them after you have turned your PC on i.e. when it is going through the intitial BIOS reading etc. I had a problem once due to viruses and messed up my PC completely. I could only see the boot screens but not anything much beyond as it kept rebooting itself. I had to call Dell (my OEM) and they resolved it by charging me £35. They asked me to press something like this and retrieve the factory-refreshed state of my PC including OS. May be it is worth trying your OEM site and also online blogs to find out how you can do that? It is really effective, but the worst part is that you lose EVERYTHING. Your refreshed PC will be as if you just bought it.
I also agree with @tjennings answer that you could use imaging and keep them separate from your computer hard-drive.
I've used Clonezilla (Free, Open Source) to create a custom Ubuntu installation that could be installed in 15 minutes, including non standard apps. The same can be done for Windows of course. Just make your installation, add all software you need, then create an image. Best is to copy this to another harddisk. Then test it! Maybe document it so you can repeat the creation of the image later without too much effort. And as your preferences change, you can be certain that there is always something to do to complete the setup.
Personally I use a variety of backup software, but what I've been using lately is Comodo BackUp. You can clone a drive, or just run a full backup (preferably on an external drive or on a network drive), and when you want to restore it (even to bare metal), you just drop in the restore disk and point it to the proper location.
