What I like about using custom menus in Xfce4 is that you are able to reuse them in any Xfce distro just by copying a few folders on to your new install and adding new menu launchers to the panel and pointing at your menus.
In this video I'm using a different distro(SaleneOS) but it's exactly the same in LMDE Xfce
Video at http://lin.me.uk/saline/why-custom-menus.mp4
I put some together 3 months ago and haven't stopped using them.
I got the info from here http://wiki.xfce.org/howto/customize-menu