Toms Hardware had a very summary of the whole anti alias stuff:
http://www.tomshardware.com/reviews/anti-aliasing-nvidia-geforce-amd-radeon,2868-3.html
For myself I think this anti alias is complete unnessary. The resolution of the monitors is already almost that high, that it is very hard two distinguish pixels (depends of course of your setup, like screen size, dpi, viewing distance, etc…). But if I would get the impression that there are too much aliasing artifacts I have an very easy solution
(which not every can do): I wear (weak) glasses. I just put them off, afterwards everything I can still see fine, but its slightly smoothed => no stairs 