Purely for the sake of nostalgia, I'd like to virtualize a couple old versions of Debian. For this example, I'll use 2.2.
2.2 (Potato) has XFree86 v3.3.6. In VMware Player 4 I can successfully use the provided SCSI controller, NIC, and possibly the sound (not sure if old kernels have the necessary driver). Can't find the needed video driver, so it works fine in console mode but it'd be fun to run X on it as well.
I don't think I was quite so successful with Virtualbox; it might have been something with the emulated IDE controller, but I don't think it would boot. Sound should be easier to do (VB can emulate an SB16, which Linux 2.2 and 2.4 had drivers for), but again, forget about the video.
Any suggestions? Microsoft Virtual PC emulates actual video hardware (S3 Trio 64) but I've heard it doesn't like Linux so much. I seem to recall that VMware /used/ to support such old versions of Linux.