OS on a logical drive by itself?

I've often heard that the OS should be on a drive (logical drive) by itself so that, when it gets a problem, you can just re-install a new copy of the OS on that drive. However, isn't the OS modified when you install programs? Where would you install them? Can someone explain the procedure for this and how it works? It has always confused me and, if if works as I understand, I'd like to try it.

The operating system, along with all installed applications programs should be installed on a single drive/partition. All user data files etc should be stored on a separate drive or partition. There are several advantages to this - first it keeps the system drive at a reasonable size (40GB is more than adequate unless you have masses of extremely large installed apps. Second it enables you to make regular backup images (using something like Acronis True Image - get a free trial download). Tis enables you to recover your system including all configuration settings, installed update and applications programs in about ten minutes as opposed to having to reinstall the op sys and recover all your apps which is hours at least if not days - and some stuff is likely to be irrecoverable. The image should be stored on the data drive and, using standard compression in Acronis would be about half the used size of the drive being imaged. It's a good idea to save the three most recent images. The images can also me mounted as a virtual drive to recover individual files or folders as well as recovering the entire drive. It can be used to recover from anything such as bad installs, malware, file corruption etc.

Where the data drive is just a partition of the same drive on which the system is stored a copy of the images should also be kept on external media as physical failure of the hard drive will mean simultaneous loss of both. I persoanlly back up my entire data drive (including the system drive images) to an external usb hard drive. (To of them in fact - I've got a lot of time and money invested in what I store on my pc!)

Thank you very much for your detailed response. I would like to ask you for some clarifications, but I am traveling and, at this time, only have time for a quick reply. If you would, please monitor this thread for a few more days so I can have time to post my questions. Thanks again........

I'll do that.