Exchange 2000 in an Domain Controller

Hi,

My question is:
Is it recommended to install Exchange 2000 on a Schema Master, or any other PC having Active Directory Installed? Wouldn’t it overload the PC.

Moreover what if we install DNS and DHCP on an Active Directory PC or even on Schema Master with or without Exchange 2000.

The number of users in our enviromnent are nearly 200 and the Server is Compaq ML 330, G2, P3 1GHz.

Thanks.