37-on-1

I had made it only till 5 - RH Linux 6.2, Win98, Win2k Pro, QNX RTP and BeOS 5 Pro. Although i could have managed to push in 2 more, DOS 6.22 and Win3.1, I lost my patience after that. This guy managed till 37!!. He was able to put 37 operating systems on a single PC.