"You may also find that some (a lot?) of programs that work with Win 98 won't work with a 32-bit OS like Vista or XP."
Win98 is a hybrid 16/32 bit OS. Virtually all applications that work in Win98 will work in XP - Vista is another matter.
PS: The converse is not true. You can try solutions like
KernelEx v0.3.6 released! - MSFN Forums to allow some XP only apps to run on 98SE