The store.exe process is allocating more memory than usual
After applying Microsoft Exchange 2003 SP1/SP2 you may seen an error “the store.exe process is allocating more memory than usual”; The performance counters and tresholds have been changed with SP1/SP2 and they need to be adjusted in order to stop these alerts from being generated by your SBS/Exchange server: 

1. Click Start, and then click Server Management. 
2. Expand Standard Management, and then click Monitoring and Reporting. 
3. Click Change Alert Notifications, and then click the Performance Counters tab in the Alert Notifications dialog box that appears. 
4. In the Name list, click store.exe private bytes STORE, and then click Edit. 
5. In the Change threshold to box, type a new threshold value that is greater than the current value and that does not trigger a Small Business Server 2003 critical alert. 
6. Click OK two times.

For additional information about how to configure monitoring and alerts, search for “Monitor your server” in the Help and Support Center in Small Business Server 2003. 

Here is some information about this alert: 867628 Monitoring programs report that the Store.exe process consumes additional memory after you install Exchange Server 2003 SP1 

http://support.microsoft.com/default.aspx?scid=kb;EN-US;867628