Shoutbox

Outlook has more updates and is continued to be updated, it also has some features which OE doesn't.  I think it depends on your machine and how much you like your set-up with OE already.  Personally I love Outlook 2007 and it is heaps better than 2002 which I upgraded from (all this is my personal experience), but it is heavier to begin with, just like anything with more features.  If you are happy with OE then keep with it, but if you are looking for that bit more then try out Outlook.  I think microsoft still has a "try out office 2007 products" kinda thing on the office site still which you can try out online before having to make the switch over (it will run slow in that because of it not being the actual program).  Just some things for you to contemplate.