Apparently there is some complicated way of trying to get this to work ith the nvidia drivers andd xinerama but it never worked for me.
Well, this has all changed since fedora 15. All of the hardware acceleration I need is in the nourveau drivers. It runs the desktop great.

Monitor suport is so easy with these drivers. Simply plug the monitor in and it works - no configuration necessary. If you want to rotate one monitor, open system-settings->displays and select the rotation desired.

It works great and you can touch either monitor's top left corner to bring up activities mode in Gnome 3. I still prefer the hot key. Its amazing how efficient my computer usage is with Gnome 3. At first it was so different. Now I hate it when I find myself on a computer with anything else.
Sure these drivers get a few less fps than the closed drivers but nothing is noticeable as I am not playing games and the convenience of not having to deal with the nvidia drivers is amazing.
UPDATE: Not only is this so totally easy. It also remembers the settings when you log back in and reconect the monitor without even having to visit display preferences.
I wish there were not so many problems with doing simple everyday things on linux like hooking up a second monitor and getting the fonts to behave.
I am not on ubuntu anymore. I am on Debian based Crunchbang. Unfortunately whenever I try and hook my second monitor up to my linux box the font on my monitor is so blurry and induces a headache. And I am running the official ATI linux driver. So I have just given up and resigned myself to just using my big monitor with my windows laptop.
Nouveau is also the default driver for ubuntu I believe. Not sure, you can find more info here :::link:::
Are these universal for debian as well?