I didn’t know about Rainmeter until I saw awesome customized desktop of a friend of mine. Rainmeter is very light and open source. This screenshot is of my desktop (yeah mine is simple 😛 ). Google “rainmeter themes” to find more. Only problems I have are that I can’t find a Start menu with search option to replace the Windows 7 Start menu and I can’t get real-time previews from rainmeter task bar. I’m currently searching for a solution and trying with Emerge Desktop which is also light and open source 😛 .