I recently found a hard drive with Windows 95 on it.
It wouldn't boot in any PC as it had too many corrupt files.
I tried to attach it as a slave but Vista couldn't read the drive at all as it wasn't NTSC formatted.
Luckally I had just installed Windows 2000 on a crappy PC and I put it as a slave on that and was able to retrieve a whole heap of historic documents from the drive.
In short... the pc might not be great but it'd be good for testing old crappy equipment without pulling apart your nicer stuff.