I get a nice smooth 50-70 FPS now with 2X AA (and Medium Post Processing as a test; not sure if even really implemented yet tho) but my VRAM usage is at like 986 megs. So likely my fps tanks at 4x and Ultra (whether or not Ultra is yet implemented) were likely full vram. Shoulda realized and at least monitored earlier; not sure why I didn't. Oh well Caspian was just this weekend anyway.
Next upgrade was probably gonna be 2GB card(s), definitely now. 1920x1200 btw...