I think the Ubuntu one should've included the Ubuntu logo instead of the Penguin. The Penguin sorta denotes the entire category of Linux Distros. An Ubuntu specific one seems more appropriate.
Here's what I was aiming for. The basic style as the background, the title as the name, and the main logo. Windows logo for windows...Apple for macs...Penguin for Linux. Thank you for your input, however.
the linux one needs beter text and watermark, or design like the vista one, and like some1 else said, use ubuntu symbol
also, the windows one looks like it should be rounded but there is a rectangular black border around it