Upgrading Contact Management from 2.6 to 4.0 SP1

Hi Experts, I am upgrading a system from 2.60A to 4.0 SP1 and I have a question about upgrading Contact Management. My reason is because 2.60A has both Contacts and Prospects but 4.0 only has Contacts and the client only uses Prospects in 2.60A and NOT Contacts. During the upgrade does anyone know if the Prospects are created as Contacts or ignored. Thanks.