Truth be told though, any particular reason why you want the new Office?
A lot of the newer Office features are really only useful for collaboration with other people who have already got the latest Office. For me, 2007 hit the spot with the ribbon and easy to use features which make your documents look pro (i.e. templates for table colour schemes, powerpoint presentations, etc) as well as the technical features (i.e. larger spreadsheets). But really, if you don't have a "need" for it, it's difficult to justify the upgrade.
ps. I only just moved to 2007 from 2003. I still predominantly use 2003 unless I have a gigantic spreadsheet or I need to make my document look pretty before sending it to a design house to make it perfect.