Afaik the situation on windows > XP has improved in the last few years, and windows vista and 7 worked fine, but only the 32-bit variants.
I however have taken MS' upgrade offer with win8, and converted all my old licenses to 64-bit in that step, so I have to drag out ancient stuff from the attic to do such things.
You'll probably need some VM solution for dos now.
OTOH, if you have the startup .o's, the pascal part should be doable on any OS now, since there is an internal assembler and linker for the pascal parts.