I do know how to do outlook programming, so that's the way I'd go.
But, for the general user Bob has the right idea. You can easily export addresses to your choice of file, update them, and then re-import them. I'd use Excel, the Proper (or Upper, depending on cap pref.) function, and have it done inside 2 minutes, depending on the time it took the computer to open excel.
The Export/Import wizard is in the File menu. It's a bit esoteric in its setup, but I'm sure you can figure it out. Be warned that it's not installed by default (although the menu item is there) so you might need the cd handy.
However, I suspect this is too little information too late. Hope your day goes well. When it comes to work, I have repeatedly had this lesson driven home: "The difference between a good day and a bad day is entirely dependant on your attitude."
Combine that with the complete refusal to carrying any work stress outside the workplace, and I've worked quite happily in some real hellholes.