Select Top 1000000 dbo.tblComputers.Computername,
  dbo.tblComputers.ComputerUnique, Web40OSName.OSname,
  dbo.tblOperatingsystem.Description, dbo.tblDiskdrives.Caption,
  Cast(Cast(dbo.tblDiskdrives.Freespace As bigint) / 1024 / 1024 As numeric) As
  Free, Floor(Cast(Cast(dbo.tblDiskdrives.Freespace As bigint) / 1024 /
  1024 As numeric) / Cast(Cast(dbo.tblDiskdrives.Size As bigint) / 1024 /
  1024 As numeric) * 100) As Freepct, Cast(Cast(dbo.tblDiskdrives.Size
  As bigint) / 1024 / 1024 As numeric) As [Total size],
  dbo.tblDiskdrives.Lastchanged As [Last changed], Web40OSName.Compimage As
  icon, tblCompCustom.Custom1
From dbo.tblComputers Inner Join
  dbo.tblDiskdrives On dbo.tblComputers.Computername =
    dbo.tblDiskdrives.Computername Inner Join
  dbo.tblOperatingsystem On dbo.tblComputers.Computername =
    dbo.tblOperatingsystem.Computername Inner Join
  dbo.web40ActiveComputers On dbo.tblComputers.Computername =
    dbo.web40ActiveComputers.Computername Inner Join
  Web40OSName On Web40OSName.Computername = dbo.tblComputers.Computername
  Inner Join
  tblComputersystem On dbo.tblComputers.Computername =
    tblComputersystem.Computername Inner Join
  tblCompCustom On dbo.tblComputers.Computername = tblCompCustom.Computername
Where Floor(Cast(Cast(dbo.tblDiskdrives.Freespace As bigint) / 1024 /
  1024 As numeric) / Cast(Cast(dbo.tblDiskdrives.Size As bigint) / 1024 /
  1024 As numeric) * 100) <= 20 And Cast(Cast(dbo.tblDiskdrives.Size As bigint)
  / 1024 / 1024 As numeric) <> 0 And tblComputersystem.Domainrole > 1 And
  dbo.tblDiskdrives.DriveType = '3' And tblCompCustom.Custom1 = '1825'
Order By Floor(Cast(Cast(dbo.tblDiskdrives.Freespace As bigint) / 1024 /
  1024 As numeric) / Cast(Cast(dbo.tblDiskdrives.Size As bigint) / 1024 /
  1024 As numeric) * 100), Cast(Cast(dbo.tblDiskdrives.Freespace As bigint) /
  1024 / 1024 As numeric), dbo.tblDiskdrives.Caption