After a LOT of experimenting with Nvidia forced antialiasing in UE3 games (Mass Effect 1-3, Quantum Conundrum, X-Com, Mirror's Edge and others), I've stumbled across something that at least improved the situation in Mass Effect 2 by an order of magnitude in my opinion.
The standard AA bits for Mass Effect 2 in the Nvidia drivers is 0x080100C5. While this gives access to multisampling modes, it still leaves a lot to be desired when it comes to image quality. IQ is sharp but there is a lot of shimmering along edges (despite having set Negative LOD to Clamp), which is really annoying.
I happened upon another set of compatibility bits on the web, originally intended to improve compatibility with SLI rendering. The set is 0x000100B5.
Not only did these bits reduce the performance hit induced by MSAA/CSAA, there is also almost no edge shimmering. I have a single GPU (560Ti-448) so I don't need these bits for SLI compatibility, but they made a huge difference in image quality in my opinion. If they don't work for you, try 0x080100B5 instead).
However, and this is also the question: neither the standard antialiasing bits nor this set allows applying antialiasing to transparent textures (for example the text labels on the Normandy's interior walls, or the cargo nets in the Migrant Fleet ships. The only way I've seen how to get them antialiased as well is to either force fullscreen SGSSAA (which induces a huge performance hit and requires manually forcing a negative LOD bias) or use FXAA (which reduces image quality since it blurs the entire screen). With the standard or tweaked AA bits above, enabling any of TrMSAA, TrSSAA or TrSGSSAA has no effect whatsoever.
I wonder if there is anyone out there who has discovered a way of enabling transparency antialiasing in this game without resorting to fullscreen SGSSAA or FXAA? (In Mass Effect 1, setting Transparency Antialiasing to a Supersampling method (but not Sparse Grid) works fine with the default AA bits, but not so in ME2).