"AeroVG" theme is one of the most popular themes available for Windows Vista created by Vishal Gupta,MVP @ AskVG.com. It provides excellent transparency in Taskbar, Startmenu, Explorer, etc. It also changes lots of visual things like menubar, addressbar, progressbar and much more.
Recently the first beta of "AeroVG Se7en" theme is made available for download.
You can download it using following link: