You can change the number of desktops on MSVDM.... To a max of 8 I believe, or as little as 2. I don't have it installed right now, but I did about a year ago and it most definately had the option to change the number of desktop's then.

I don't like MSVDM much though, about the only thing it's usefull for is changing your background picture quickly To many of the windows are shared from desktop-to-desktop.