From: 440gtx on
The Windows 2003 DDK is the latest DDK that has everything you need;
help, headers, build, etc. You can use that DDK to target VxD's for
Windows 3.x, Windows 95, Windows 98, and Windows Millenium. VxD's are
32-bit by the way. There is also a discussion group for them:
comp.os.ms-windows.programmer.vxd though you will probably be pretty
lonely.