Rebooting Exchange Server 2003

I recently got a job in the IT dept of a small company and have found the the head IT guy knows nothing. I am taking upon myself to do some simple tasks like apply needed updates to the servers such as Exchange. The server is currenlty running MS Server 2003 SPK2 which provides internal email and OWA. Is there anything I should be aware of concerned about before apply the MS updates or do the reboot?