Just one thing to watch out for with 2010, if you use outlook on a Windows Server 2008 via Remote desktop, you need a volume license serial to install it, otherwise it won't install on a Server with Remote desktop enabled.
really, really annoying. I emailed MS and they advised me to buy 5 copies of Office 2010 just so I could get a volume license and then install one copy of Outlook onto it.
So, I've got Office 2010 on my PC and Outlook 2007 on the server.