When I was reading Computerera (September 2007) Magazine I read an article in it.
In that they given about a small utility to make windows transparent.
I downloaded that utility and it is working nice. That utility is vitrite.
Download and install it. After installation the vitrite will appear at the tray icons.
To make windows transparnt press "CTRL+SHIFT+0,9,8,7,6,5,4,3,2,1," Simultaneously accoriding to your requirement of transparancy.