InfoPath - MOSS User Information List as Data Connection - Exclude groups

Question

I have an InfoPath form where I want to place a drop down list to select a user from a MOSS server.

I added a Data Connection in InfoPath to the User Information List list in my MOSS server. It works well, but the values I get are:

DOMAIN\administrator
SharePoint Owners
SharePoint Visitors
SharePoint Members
NT AUTHORITY\local service
System Account

Is there a way in InfoPath (or MOSS) to filter the list so it doesn't include groups?

Bonus question: Is there a way to filter it so system accounts are not shown?