If you are looking for a touch screen, then the 12" screen requirement is going to make it hard to find. There just aren't that many systems out there that are touch (The Iconia W500, which I own and love, is one but you ruled it out because of a 10" screen) that are not windows 8 systems, and while win 7 MIGHT install on one of those, it also might not.
You could always do a windows 8 tablet with a windows 7 vm running at boot.
If a stylus is fine, then you have a whole sew of possibilities. I also own a gateway cx2750 running win 7 and I used it for meetings until very recently simply because the handwriting recognition in win7, once trained is simply amazing. It has the screen size and res you are looking for, but its not light. Of course I have the extended battery in mine, which makes hodling the damned thing a lot easier, even if it is heavier.