I have just purchased this game, and based upon the dwindling support, I am starting to question that decision. Anyway...it is still a bit of fun.
For those frustrated Vista users, of which I am also one, I can only offer the following advice, which will allow you to play after some mucking about. I, too, have exactly the same connectivity problem under Vista. I then installed Microsoft Virtual PC 2007 (free download), pulled out an old Windows XP license and installed it as a virtual PC. Upgrade to SP2 and voila, DiF works within a Window in Vista...no dual booting.
Unfortunately, you need an XP license, but I am sure most of this group have been around long enough for that.