At work, I have no choice. Windows XP professional on corporate network.
At home we have three x86 tower systems, an x86 laptop, my PPC system and an ancient A2000HD (mostly retired).
Windows 7, Windows XP, QNX, OS4 and AmigaOS 3.1.
At home, I use OS4 and QNX the most and occasionally AmigaOS 3.1 for old times sake.
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redfox