Virtual Memory Fragmentation Event ID 9582

I'm have a Dell PowerEdge2600 Server with (4) Xeon Processors, 4 GB of RAM, and a RAID 5 configuration.  This system is configured with Microsoft Windows 2000 Server w/SP4 and also runs Microsoft Exchange 2000 Enterprise Server.  It is the primary mail server for approximately 50 mailboxes, and performs no other file or print services. 

Roughly every week or so I had been receiving Application Error 9582 alerting me that the virtual memory was fragmented so much that I needed to restart Exchange.   Although the server performance never seemed to be effected, except for two occasions when these were accompanied by an occurrence where the system rebooted itself, and the only evidence of this was Event ID 6008 indicating that a previous system shutdown was unexpected.  I noticed that Microsoft recommends adding the /3GB switch to the boot.ini file on a W2K Advanced Server system, but this flag is not supported in W2K Server.  I then did the following according to the following Technet article: Troubleshooting Microsoft Exchange 2000 Server Performance:

If 9582 warnings are still being logged, then you must perform a registry change. This registry change is acceptable as long as there is an adequate amount of RAM available on the server.  Make sure the counter indicates more than 200MB.

1. 
   
2. 
   

   Change HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\HeapDeCommitFreeBlockThreshold to equal 262144.

Since making this registry change I have not seen the errors in 2.5 days. 

Also, when I allow Dell to examine my "Current Configuration" I'm told I have 81.98% Virtual Memory available.

Given these virtual memory errors is it recommended that I move to Windows 2000 Advanced Server?  If not, are these any other steps I can take to optimize my system thereby eliminating any virtual memory bottlenecks? 

Thank you for your help.