There is a procedure using Thunderbird. However, TechHit specializes in this migration. You can find its utility suite here.
Unless you absolutely need Entourage, then I suggest that you stick with Apple's free triumvirate of Mail, Address Book, and iCal. In this case, you can use the much less expensive O2M.
Hey,
Try using PST Converter Pro. See here www.pstconverterpro.com. I think its far better than O2M and TechHit solutions. Only $10 on sale. I bought this after trying many solutions. Hope it would help you.