I use Windows Xp Pro mostly on 4 different laptops--3 Thinkpads and one Sony Vaio. I have OS 3.1 on both my Amigas. I had OS 3.9 on my A4000 but the disk crashed and I haven't had time to reinstall it. I use TOS 2.6 on my Atari Mega ST and Mega STE. I also have an older Thinkpad that is just about as vintage as my Amigas--1998--and it multiboots MSDOS, several versions of Windows, Linux and OS/2. I only really use DOS and Windows 2000 on this laptop. DOS for such things as my eprom burner and Parcp to transfer files from my Mega ST and a few other programs I use occasionally that require MSDOS and won't work in Windows. My Amigas also multiboot but not different OSes, different graphic systems. My A2500 multiboots EGS, Picasso 96 and Cybergraphics on it's EGS spectrum card and my A4000 multiboots Picasso 96 and Cybergraphics on a Picasso II.
I also have a a Nokia phone with Symbian but the OS is really irrelevant, the only thing I use it for is Skype via wifi.
I just bought an Ibook G4 with a broken LCD and the new LCD will arrive next week so I will have some version of OSX for a while but my relationships with Macs never last. Usually, one of my friends or associates wants it more than I do and I end up selling it. I've already been asked about this one and I haven't even fixed the LCD or tested it to see if anything else is wrong with it.
Oh, and I should mention Palm OS. I have 3 Palm Pilots in my collection with 3 different versions of Palm OS from 4.1 to Garnet
