If you are not a programmer then you should know this:
Almost all good(and some bad) programs were writen in C or C++ language.
C and C++ is what you need to learn if you want to port existing programs to 9x platform.
Microsoft Visual C++ 6.0 is the latest that works in win95, 98 and WinME.
Visual Studio 2005 is the last which may produce 9x compatible programs.
The only real alternative to Visual Studio is Borland C++ Builder v6.0.
There are many alternative "free" C++ compilers but they are all under some crazy license,
latest version of them do not work on 9x platform and they can not produce 9x compatible
programs.
here is some of them:
MinGW (GCC) Minimalist GNU for Windows
http://www.mingw.org
Open Watcom C/C++ Compiler
http://www.openwatcom.org
LCC-Win
https://www.cs.virginia.edu/~lcc-win32/
Orange C/C++ Compiler
http://www.members.tripod.com/~ladsoft/orange_c_compiler.html
Pelles C (Based on LCC)
http://www.smorgasbordet.com/pellesc/
Dev-C++ is just IDE which use MinGW (GCC) compiler.