Speaking of old cards, i own a real Roland Sound Canvas board (SCC-1) since 1993, (if i remember correctly, the price was near 400US$). I have noticed that since win98, there is a "microsoft synthetizer" thing that can be used for midi playback. This is a soft Sound Canvas very much like the old Virtual Sound Canvas. The GS logo is displayed in the info panel. I can say that the samples do sound pretty much like those on the real board, _but_ there is a lot of stuff missing. Among things, all the reverb/chorus effects are missing, and many sound sets are not present at all.
Anyway, to the point. I will try to explain things a little bit, because its natural that most don't get this MIDI thing at all
Not all MIDI files are equal, quality varies very much, because most are custom tailored for specific sound boards / midi modules. Some are very simple, some are complex, some use many instruments, some use different techniques to achieve the same. An early attempt for standarization emerged and was called GM (General Midi), its like a default basic that manufacturers agreed to. Before it, even basic sound instrument positions were different (example, in GM drum sets are supposed to be in part 10).
On top of GM, Roland made GS (kind of extension for GM) and later Yamaha introduced XG, another extension. For this reason, there are midi files custom tailored for, GM, GS, XG, and more recently, "Super Sound Canvas" (SC-88 and newer roland modules).
Because i have a real board, i could try an analog recording of a certain midi file, and maybe you can compare it with your midi reproduction to see if they are the same.
Hint! Hint! Warcraft II CD audio music was actually Roland SC-55 MIDI recorded!!! I have the midi files to verify it
Most ppl at the time had FM synthetizers, that were misused as cheap MIDI devices (something for which they were *not* designed to do). And could never enjoy the real music most games from 93~98 had in them. Oh, and there was the net, how godly impressive people's compositions are! You should check out the
Sound Canvas User Group (SCUG) compos

And, there are so many
Classics! hehe.
BTW: Some roland modules (and the card i have) had this cool bug where you could do real overdrive/distort effects by tricking the reverb/chorus system

(the
Sound Canvas Pipe Organ Project exploits these