I'm amazed that you lose points for not having Win8.
2gb is more than enough, a 770 is 2gb and that'll come pretty close to maxing the game out I reckon.
Oh and just for the record, this is the first thread I've had to lock. An untarnished record of approaching a year has now been ruined, bceause certain people aren't able to have a mature discussion.
You know who you are.
If you want to start another thread, go for it. But be warned: one wrong word and it's gone. If people can't discuss things like adults then I've got plenty more locks to go around.
No, just run the thing I linked to above, Windows will sort it out.
Once it's installed, reboot, and try again.
To be sure, play for an hour or so, reboot again and see if it's still cool. If not, let me know.