This will probably get moved to another forum, but this is how I did it.
In outlook, I exported the address book in a CSV format (or perhaps it was tab delimited - don't remember). Then, usb drive it to your iMac, or email, or drag and drop from your home network, and import into Address Book. You'll get a dialog to help line up the data. No biggy. If it doesn't work the way you want it to, delete it all from Address Book and re-import.
