A quick look through the Entourage menus doesn't list Outlook as an import option. Contacts and email wouldn't be a problem. Calendar entries would be though.

BTW, Outlook for Mac is an OS9 app and I don't believe it supports non-Exchange accouts. Could be wrong though.

If you're going to be using Virrtual PC, it may be worth using Outlook in that for old data and switching to a more open format for your new data.