Should I get Windows 7, 8 or 10?
Should I get Windows 7, 8 or 10?
The Reddit post suggests the Microsoft software swap is more affordable and perceived as safer.
If it was a built system (like a dell or similar) then you'll need a new license but if you bought a copy of windows 7 then it's transferable. 7 or 8 for now.. 8 is slightly better at resource management (particularly memory) but I'd wait till 6 months after launch for 10.. Give them time to work out the major bugs and for drivers to be more widely available.