THE OFFICIAL BLOG OF THE SBS DIVA

Do you have over 1 GB of RAM?  Did you notice this in the release notes...

Event 9665: Update to recommended memory settings for running Exchange 
Server 2003 SP1 on Windows Server 2003.

When you are running Exchange 2003 SP1 on Windows Server 2003 with more than 
1 GB of RAM, it is recommended that you set the SystemPages registry key to 
zero. This recommendation contrasts with the recommendation for Windows 2000 
Server, which is to set SystemPages to a value between 24000 and 31000.
The recommended memory settings for Exchange 2003 SP1 on Windows Server 2003 
with more than 1 GB of RAM are as follows:

If you host mailboxes or public folders on a server with more than 1 GB of 
RAM, make sure that the boot.ini file contains the /3GB switch.
When you use the /3GB switch, add the /userva switch to the boot.ini file 
and set the switch to a value between 2970 and 3030.
When you use the /3GB switch, set the hexadecimal value of the following 
registry key to 0x00040000:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\HeapDeCommitFreeBlockThreshold
Set the decimal value of the following registry key to zero:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management\SystemPages
If you set SystemPages to the Windows 2000 Server recommended value of 
between 24000 and 31000, an Event 9665 will appear in the event log.

-Trevor