Hi Tracy,
The following screenshot is using CRM2011 but the V4.0 advanced find designer is pretty much the same.
Here I'm returning phone calls that were completed (actual end is automatically updated when an activity is completed) is in a given month (September) and is linked to an opportunity that IS open (actual close does not contain data) or WAS open (actual close
on or after 1st of October).
I'd also look at the Report Wizard for this as you will be able to create groupings by staff member and add a record count should you wish to avoid exporting to Excel.

I hope that helps,
Rob
Microsoft Certified Technology Specialist (CRM) GAP Consulting Ltd Microsoft Community Contributor Award 2011