Macintosh computers (with system 8.1-9.2) can run Windows '95 - '98 - ME - 2000 through an emulator called Virtual PC v5.0. Macs with OS X 10.x or higher can run Windows XP through Virtual PC v6.0.
I highly reccomend using a PowerMac dual G4 or G5 for this emulator seeing as any slower processor would hinder your ability to move around quickly between the two environments.
But if you're looking to run them both on a PC platform, it's not possible and there is no emulator.