Java HotSpot Virtual Machine

I am seeing an interesting occurance. I am running jdk 1.5.0_6 on Windows 2003. I am running an application that solely does network operations (little to no file I/O), but a lot of them. I am using the -server JVM and using the UseLargePages parameter. Now the interesting part: if I set the Xmx and Xms to 96 meg, the used memory shown in TaskManager is a little larger than the calculated used memory in Java (this is as always). However, if I set Xmx and Xms to 128 meg, the used memory shown in TaskManager drops to less than half of what Java says is used. This behavior has been confirmed by another person running the same application.

Any ideas why this is?

Pete Loveall