xp
I prefer using xp on office, because there no nagging messages, and after a period of time most of the important problems in the software have been sorted out. If I keep to the standard software - why would I need support.If I use XP for every day data, so why would I want to change something that is not broken. Win7 and Win8 have their advantages, but for every day data they are still bloated compare to XP.