Both are 64 bit versions so as to not be strangely locked to 3.5gb ram like 32 bit is. assume both are running off an intel 1150 haswell chip/mobo. 8.1 is newer and they're both around $150-$200 USD locally with 8 being strangely cheaper. 8.1 is truthfully designed for only tablet and lolthinksit'saPC tablets and it not optimized for KBM controls even though they're barely still useable when using 8 on desktops. MS provides security updates to 8.1 unlike older versions of defender which are "discontinued" Support status. Win 7 has more programs than 8, it is optimized for KBM. programs for games would probably have more compatiblity. plus it is based off of vista/XP instead of touchscreen. bungie, what do? also explain your reasons please. [spoiler]it's not really a poll so you can participate instead of clicking a button and scurrying off[/spoiler]