Actually, just did some searching, and it looks like I can. It's just not easy. I've got to export to an Outlook Express-readable file, then covert that over to Outlook. And do it once for addresses, then calendar, then emails. Blech.
And he was using Nutscrape back when it was cool (3.x) and was far superior to IE or anything else out there. Problem is, he never got away from it like most of us did when it started to suck (> 4.0)