We are currently in the process of switching all company computers from Trend Micro to Kaspersky AntiVirus.  I have created two separate reports to show me which computers have each application installed.  I now want a report to show me any computers that have neither of these programs installed.  This is what I have currently:
SELECT     TOP 100 PERCENT dbo.tblComputers.Computername AS Computer, dbo.tblFileVersions.Lastchanged, dbo.tblFileVersions.FilePathfull, 
                      dbo.tblFileVersions.[Found]
FROM         dbo.tblComputers INNER JOIN
                      dbo.tblComputersystem ON dbo.tblComputers.Computername = dbo.tblComputersystem.Computername LEFT OUTER JOIN
                      dbo.tblOperatingsystem ON dbo.tblComputers.Computername = dbo.tblOperatingsystem.Computername LEFT OUTER JOIN
                      dbo.tblFileVersions ON dbo.tblComputers.Computername = dbo.tblFileVersions.Computername
WHERE     (dbo.tblFileVersions.FilePathfull LIKE '%PccNTMon%') AND (dbo.tblFileVersions.[Found] = 0) OR
                      (dbo.tblFileVersions.FilePathfull LIKE '%avp.exe%') AND (dbo.tblFileVersions.[Found] = 0)
ORDER BY dbo.tblComputers.Computername
This report doesn't show me exactly what I want though.  It just shows me a combination of all the computers that don't have one or the other, but not both.  I have seen a few other people in the forums having a similar issue, but because of my limited SQL skills, I'm not able to apply their solutions to my particular problem.  
Would anyone mind helping me out?
Thanks
-Chris