I have to admit right up front that I am a huge fan of Microsofts Windows Home Server.
Much as it's name implies it's a server for the home - all clear? no? Let me explain!!
Generally in an office environment there is a computer dedicated to providing services of one kind or another to any number of users at the same time within that networked environment. These services could be just to provide storage space so that users can store data of any kind in an area other than on their own machine - for backups of their machine for instance, or as a store for less frequently used files, so as not to clog up their own PC's hard disk with little used files. This computer is generally called a file server or just a server for short.
Windows Home Server (WHS) is a server for the home - no surprise there then! As these days most homes have more than one PC - it makes sense to use server technology to backup all of the machines in the home and to centralise all the data that all the machines are likely to use such as pictures, music and video. Any files stored centrally like this can be marked to be duplicated over multiple disc drives, (if you have more than one installed of course!), so if you have a hard disc failure on your WHS machine you shouldn't lose any data - fantastic!
Another great thing about WHS is the fact that without any need for intervention from the user, it goes around all of your PCs once a day and backs them up automatically. But it gets better - if you had the same file on a number of PCs; WHS has the intelligence to store that file, (or even just large chunks of it), just the once. So if you had a 100 Mb file on 4 PCs, you wouldn't use up 400 Mb on the WHS, you would use a little over the original 100 Mb - excellent!
Backups of course are no use without a restore capability and WHS delivers on this front as well. If you manage to trash your machine by loading up some dodgy software or a hard disc trashes itself - then you can use the restore capability to totally reinstate an image, (complete copy), of the drive from an appropriately dated backup.
WHS is also accessible over the web if you wish it to be - so if you are at a family members house and you want to share photos of your vacation, or share (obviously non-copyrighted....) music - you can surf to your individually allocated web address and download the files you want to their machine. As a seperate task WHS - can be a web server; so you can host web pages from your home machine, bandwidth permitting.
Every home should have one!