Re: Nvidia vs. nouveau
I will make two corrections.
1. 3D does work in nouveau, and is good enough for playing basic 3d games (neverball/neverputt, quake3 etc, doom3 doesn't run) and running kwin 3d compositing effects in kde 4.
2. The multi monitor support is very very good in nouveau, and it supports randr 1.2, which makes it better than nvidia driver. I still cannot believe that there is no randr 1.2 support in nvidia driver. The biggest problem for me with twinview is that when one creates two desktops using twinview, it behaves like a single big desktop with double horizontal resolution. As a result, all apps open at the center, split between the displays, which makes it annoying. And not to mention full screen apps, which are spread over two monitors too. In particular forget about full screen presentations etc. (One has to use "clone" mode then.) While it is possible to do things with xorg.conf, it is tedious to do it with notebooks, which potentially connect to different external displays all the time.
However, the biggest thing that is stopping me from using nouveau full time is power management. Especially, the 9800m gs on my notebook can get very hot. Another big thing for me is gpu programming using cuda and opencl (which may not be important to most users). And vdpau is added bonus, however xv works fine for even 1080p videos on nouveau on my gpu, so I presume it should work decently on other cards as well.