Joseph sent me this article, in which the writer switches from Windows to a new MacBook Pro (the same one I own).
In doing so, he found the easiest way to import his Outlook contacts into Mac OS X Address Book was just by using Plaxo! While he was being tongue-in-cheek, I noticed Derik DeLong uses Plaxo as the Address Book store in a free dotMac service. (Like him, I still pay for my dotMac account, which is a carryover from the old free iTools days.)
Plaxo indeed a great way of importing your contacts between platforms. I use it every day to keep my Windows data in sync with my Macintosh and I can’t wait until the day my iCal calendar can sync with my work’s Exchange server via Plaxo.