And get the 1.4.5x patch from http://www.enemyengaged.com if you don't have it already.

Sure you can set the slider, but look at the image quality and benchmarks, That's the proof.

I didn't know about the bandwith problem.

But: FSAA works on 1024x 768 at 32 bits.
except not as good as it should when you compare it to 1024x768 at 16 bits.

At 32 bits it only preforms about 50% of AA per pixel, I find it difficult to explain without showing pictures so here's a textual/visual approach:
Assume that "5" is the foreground color (black) and "0" the background color (white).
A normal color blend sequence between these pixels is then 4-3-2-1. On my system FSAA4x at 32 bits generates only the first few steps: 4-3.

So it might not be as good as it should, the jaggies are softened up a bit and that shows quite clearly.