SBS2003 SMTP Configuration

Hi, we have just taken over support of an SBS2003 server which is using the POP connector. They are having some delivery issues and we thought we should turn off the POP connector and go fully with smtp. Can someone clarify that these are the steps we need to take:

1. Create MX record to point to the SBS static IP address
2. Turn POP connector off

Is that all we need to do? Should we use DNS for mail routing or use a smarthost?

Thanks in advance

Kev