I've been using something like this for my anti-aliasing (so pp effects can be used with it, the effect isn't just on the edges of objects, and it can be toggled on/off instantly) -- I render the scene to a bmap with twice the dimensions of the screen, and then render the result to the screen using one sample per pixel -- each sample being in the corner between four pixels on the larger bmap. It works like a charm. I also use it for my bloom, whether I'm using anti-aliasing or not.

Jibb