Both cards provide sufficient 4x multisampling quality to satisfy most gamers out there, although anti-aliasing of small objects and details could have been a little better.
We should note that CSAA 8x, which is supported by Nvidia GeForce 8/9 hardware, has nothing to do with true multi-sample AA 8x. In fact, this is one of the coverage-sampled antialiasing modes that stores only 4 color/Z samples, but uses 8 color lookups within its coverage sample. As you can see from the screenshot, this mode is practically the same as the regular MSAA 4x in quality.