The transparency effect in Windows Vista and 7 looks amazing. But, the context menu isn’t transparent. If you’re interested in making your context menu transparent in Windows 7 then you can try out TransConMenu developed by a user with the name Solo-Dev on DeviantArt.
The app is light and easy to use. Once started, it sits in your taskbar tray. You can click on it to bring up the options, clicking the “X” will close out the program. You can also toggle the transparency in the options. This tool also works with XP and Vista.