Question on Asus EN8400GS and EN8500GT

I don't play game, just use my computer to watch movies (avi, mkv), surf the net, photoshop & edit video (premiere pro, after effects)..Now choose a video card to match my C2D or C2Q & hook up to my 24' LCD

Asus EN8400GS 256MB Silent $49CAD
Asus EN8500GT 512MB Silent $79CAD

So for $30 different I get 256MB more + GT..but it's worthed since I don't play game..or is 256MB sufficient?

Thanks!