Glass2k

There's no doubt computer users like eye-candy windows, so it's no surprise that downloadable software solutions supposed to change a thing or two about the way the operating system looks enjoy an impressive success.
Glass2k is an application supposed to help you in this regard, as it gives you the option to add transparency to all windows on your screen using just some keyboard shortcuts.
One of the best things about this utility is that it relies on a simple and very easy to use interface, with just a few options displayed in the main window.
You can thus configure key settings, choose the Taskbar transparency, but also enable some other settings such as a beep every time you enable the see-through effect.
Still, the whole process basically comes down to this: make sure the window you wish to add transparency to is the active one and press the selected keyboard combination to enable the effect. Very easy and efficient as well.
Glass2k will quietly sit in your System Tray all the time without hampering computer performance at all, even on older machines, so Windows XP users should be delighted with it. The program is being delivered as a very light package, so it takes just a few seconds to get it to work.
All in all, Glass2k is quite a great app in case your operating system doesn't support Aero and has no opacity effects for the taskbar and program windows. Thanks to this tool, you will be able to activate full transparency to any application.