AmigaOS 3.1 and 3.9 (on my classic machine about once a month, maybe less these day this is mainly due to...)
AmigaOS 1.3 to 3.9 (emulation thanks to Amiga Forever 2012 about once a week for a quick gaming or mess around with various programs, currently trying to get back into making games.)
Aros AspireOS (Only had it for about a month, played with it on and off need more time to really set it up how I like my amiga to really get into it.)
Windows 7 (I have to say is my main machine, sorry
, i have to say though Win7 is the best MS OS I have used, why it took them this long to make a good solid OS I will never know.)
Windows XP (now and again for odd old software that wont run in Win7 or not bothered to setup in win7. both on the same machine)
Ubuntu (mainly on my Acer Aspire but I might try using Aros more on it and i do have it on my PC for when i was stick of XP and did'nt even try Vista.)
Hopeful soon AmigaOS4 which will cut my time I have to use Win7.
