Ubuntu doesn’t yet have a nice graphical way to setup dual-head. But if you can manage, you can just edit your xorg.conf directly. You can even have a look at how fedora set yours up. Here is a link about it:

https://help.ubuntu.com/community/XineramaHowTo

If in any doubt, you will find there is more understandable information online, than there is for any distrobution or OS. Perhaps due to sheer-size of people using Ubuntu. But if you still can’t manage, you can always place a support request on launchpad.

https://answers.launchpad.net/ubuntu/+tickets

There are lots of nice people there answering your specific questions and needs. And in case your wondering, the support is from the community (although a lot of canonical employees also help people out there, in the majority of cases the community is faster to reply

I think Ubuntu’s power really comes from it being both a community effort and a commercial effort. Everything is transparent, you can see, add and discuss feature specifications. It has the best bug management systeem ever: it will track all of its own bugs, but also link them back upstream when it is not a packaging bug.

Every new version contains tweaks and love from the community as well from people being paid by Canonical. The line between these two groups of people is very very thin. In reality it comes down to people being paid to do the boring stuff and the community gets to do the exciting stuff. Some people only help by providing support for free to others (also managed on launchpad), some people just write specifications (whats needs to be improved the next version), others deal with translation, etc.

Its like the hobbyist are more in control with Ubuntu than any other commerically supported distrobution. If you want stable and supported you just don’t enable the universe If you all the community love you can handle you enable the universe.

In any case, I hope you will like your new desktop. Just don’t be overwhelmed: there is a lot possible with ubuntu if you stick within the supported segment, but you can do even more if you decide to go hacking on your own.

Good reference-sites:
http://ubuntuguide.org
https://wiki.ubuntu.com/

If there is any software they don’t provide. The best place to help yourself is:
http://getdeb.net

For raid support you need to use the alternate rather than live CD for install, and manually configure the partitions. Dual monitor support is discussed here: http://ubuntuforums.org/showthread.php?t=221174. Basically, install latest 3D driver then edit the x.conf by hand.

Feisty, due in April, is supposed to be making dual monitor easier.