You do not need to buy VB in order to run RanDom. You just need the support files which may already be on your pc. I believe WinXP comes with them, but if you are using Win95-98 (not sure about WinME), you can find the run time files required by VB programs here.
http://www.microsoft.com/downloads/d...displaylang=en
For a quick map with those dimensions and many choke points, as Gandalf pointed out, you can just go to the random map creator in Dom3's game tools and adjust the mountain percentage higher and be sure to use the impassable mountains option.