When you add it all up with the freebie upgrade, we think it's finally safe to move off ol' faithful Windows 7, with the glaring disclaimer that you might want to stay put if you're a heavy Windows Media Center user. Windows 10 doesn't support or include WMC, even if you upgrade from a system that already has it installed.
That said, WMC is dead in the water now. You might want to consider finding alternative solutions--the Xbox One has largely replaced WMC in the living room as far as Microsoft's concerned--and upgrading to Windows 10 anyway. If you upgrade from a version of Windows with WMC installed, Microsoft will at least provide you with some alternative source of DVD playback later this year. In the interim, VLC is free and wonderful.
Windows 8 and 8.1
Yes. Upgrade. Do it now. There is no reason not to--again, unless you've purchased Windows 8's optional Windows Media Center add-on pack and don't want to lose access to that software.
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