I was messing around with Ubuntu and Gnomenu trying to see how close I could get them to look like vista and I couldn't find a decent Vista Start Orb for Gnomenu so I got the theme from Vista Start Menu for Gnome, edited it a little and added it to Gnomenu, it looks the real deal.

To install it extract the folder and move it to "/usr/share/gnomenu/Themes/Button"

Hope you enjoy it