Windows 7 have a nifty feature which combines the windows of opened applications under the same taskbar button. If you don't like it you can always turn it off.
If you can't copy files that are bigger than 2 or 4 GB, usually HD movies and such, on to your USB key, it's usually due to the file system the USB key is formatted to.
In this tutorial, i will show you how to create invisible folder. Very useful for users, which like to hide secret folders from other users on computer.
By default Windows calculator doesn't support order of operation, to enable the functionality you need to activate the scientific view, let me show you how.