Office has its problems, but speed is better
On my 2009 15" 2.53Ghz with a 7,200 rpm drive, first start up of Word takes 7 bounces, a short wait and then the file slides up. Quit Word and start up the same file, less than one bounce, almost to fast to see, posh it's up and running.
So I concur with the poster above, you probably have some issue in the system, HD directory fragmentation, or the like that is causing the issue.

What HD do you have, Seagate, Hitachi, etc.?
Have you tried booting up from the Install DVD and repairing the HD using Disk Utility or better yet, run Disk Warrior on the internal drive while booted up from an external HD?
You did say your disk is 80% full too, which may be causing the drive to take some time to search for the file, especially if the file is fragmented. Try temporarily freeing up some more space?
This is a difficult issue to sort out, will probably take some experimentation.
Good luck, and enjoy your new Mac! Don't let MS spoil the usually excellent user experience.


