I'm interested in writing a demo and I noticed that most of the demos
run under DOS. Is this the standard, or does this have more to do
with the fact that many of the demos are a bit dated?

I have an old Watcom C++ compiler, Visual C++ 6.0, or g++.

Does anyone have any recommendations for what compiler is best (for
speed and portability)? Should I be writing this for DOS, Windows,
both? Anyone ever take a stab at a web enabled demo?

Thanks!

-Tom