Entourage offers the ability to import contacts using a method similar to that of its Windows counterpart, Outlook. If you are moving from a Windows PC to a Mac and need to move your contacts, you can easily do this using the Import and Export features these mail clients offer. You must export contacts from your current mail client to either a tab-delimited or comma-delimited text file.
Microsoft cautions that "Importing contacts from Outlook 2000 or later can pose special difficulties because of the way in which the programs save exported files. For example, Outlook contacts that contain paragraph returns in the Notes field are not imported to Entourage correctly. Before you export contacts from Outlook, make sure the Notes fields in your contacts do not contain paragraph returns. Also, after you import, you might need to delete blank lines that appear at the top of the Address Book."
After exporting your contacts, you will need to transfer them to your Mac computer so you can import them into Entourage. The Entourage Import Assistant provides two ways to map fields: mapping fields manually, or using a mapping file you have saved previously. Generally, the first time you import contacts from a text file, you'll have to map the fields manually.
To import contacts, follow the instructions in these Knowledge Base articles: