Editing Gnome User Menu?

[Chip Witt]

Turns out that when I installed the latest beta rpm of Opera, two menu 
entries were created under User Menu -> Gnome -> Internet. Although this 
isn't xfce's fault, I was wondering if someone out there could help me. 
Adding my own entries is a snap, but I've been unable to find where the 
Gnome menu items (or the KDE items) are read from so that I can edit 
them to remove the redundancy. I know...it's always the last place you 
vi. :)

I apologize in advance if this has already been asked and answered.

Thanks.

CW