Question : Upgrading SQL Server 2000 RTM to Service Pack 4

Just started working with a server which has multiple roles, e.g., DC, SQL Server 2000 RTM and Exchange 2003.  The SQL server 2000 application has been freezing up recently and discovered Microsoft will not even support unless it is upgraded to Service Pack 4.   As it is currently still on the initial RTM service pack, I am wondering what is the process to follow moving to SP4 and what precautions should be taken (other than backing up the DB)?

Thank you!  

Answer : Upgrading SQL Server 2000 RTM to Service Pack 4

nothing else than a backup of the databases is needed...
apart from eventually testing the procedure on a test server.