(Updated on September 19, 2015) Since this article was written, Microsoft has continued to issue new versions of Windows, first Windows 8, then Windows 8.1 and now Windows 10 (only THEY can explain about their haphazard way of numbering!) Keith Paterson has written extensively about these later versions here (Windows 8 and 8.1) and here (Windows 10). - Webmaster
Evolution of the major Windows OS: Windows 1 (1985), Windows 3.0 (1990), Windows 95 (1995), Windows XP (2001), Vista (2006), Windows 7 (2009), Windows 8 (2012), Windows 8.1 (2013), Windows 10 (2015)
What's new in Windows 7
Windows 7 has a new feature called Jump Lists. When you hover over a program's icon in the Start menu or on the Task Bar, a list of items you’ve worked on recently will appear eg. if you hover over Windows Media Player's icon your recently played songs will appear. The same happens when you hover over the Word or Excel icons or your photo editor. You will find recently open documents or photos that you can click on to open straightaway.
You can leave many windows open and yet not clutter up your screen by simply dragging their borders to the edges of your screen. Drag them back to full screen anytime you want to or halfway in order to put two windows together side by side.
The new feature called "Libraries" puts similar types of files (eg. photos, songs) that are scattered all over your computer together in one location - even when they're in different folders or in your external hard disk. Thus if you have different folders, one for each of your family member's photos, you can choose the ones you like from each of them and you will find them together in one place in the library.
XP still rules
With Windows 7 you can download the Windows XP Mode which allows you to run old software while still under Windows 7 (but this is only true for the Professional and Ultimate versions).
"Goes to sleep" faster
On the positive side, Windows 7 enables your PC to "go to sleep" a tiny bit faster and resumes its earlier state a wee bit faster too.
Not missing but hidden
If you should open two Word documents and have them minimized while you open your Firefox, you will not find an icon of the second document though it is still there simply because it is hidden by the first. Similarly if you should open two sites in Firefox in two separate windows and then go on to use some other program, you will only be able to find the icon of the first, not of the second. This is because some smart guy in Microsoft thinks it is better to just let them overlap so that only the first will be visible. Again someone who switches from XP or Vista to Windows 7 will be completely baffled by this new system.
There are a number of other less-than-obvious uses that Windows 7 offers such as the Touchscreen. It will enable you to make use of the state-of-the-art touch-sensitive screens (great for those who like gadgets!). With such a tactile screen you can just throw your mouse away and let your finger do the work in its place!
After using Windows 7 for nearly two years now I must say that I have not been at all impressed by it. To me it's just another Microsoft tactic to make users spend money in buying the new OS which, apart from the artificialities have really not much new to offer the internet user. Windows XP was a gem and Microsoft would do well to just leave well alone.
Go here for my earlier review of Vista.