Creating Partitions For Installation

I will be installing a W2K Server.

Server details:
– will be a domain controller with AD installed
– will be a DNS server
– installing IIS (hosting a few web pages)
– installing Exchange 2000
– installing SQL Server 2000
– may be installing small server applications

The server has a 40 GB hard drive.

How many partitions, and of what size, should I create?