1GiB is not going to benefit you. Crank the AA up enough for it to make a difference, and everything is already running way too slow anyway. The G92/RV6xx GPU is just not fast enough to do AA past 2x-4x or so at 1920x1200 in demanding modern games. 1920x1200 with 4x or less AA is not going to use more than 512MiB of VRAM except in very rare cases.
Also, as far as jaggies are concerned, mid resolutions with AA will have fewer than higher resolutions with no AA, at least on the native res of a decent sized LCD. The only time I've found jaggies to not be prominent without AA on a 1920x1200 res LCD, was when it was 17" laptop screen with an exceedingly small dot pitch.
...rightful liberty is unobstructed action according to our will within limits drawn around us by the equal rights of others. I do not add 'within the limits of the law,' because law is often but the tyrant's will, and always so when it violates the right of an individual. -- Thomas Jefferson