[System.Reflection.Assembly]::Load("Microsoft.SharePoint, Version=12.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c") 
[System.Reflection.Assembly]::Load("Microsoft.SharePoint.Portal, Version=12.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c") 

$webapp = [Microsoft.SharePoint.Administration.SPWebApplication]::Lookup("http://<url>"); 
$total = 0

foreach($spsite in $webApp.Sites) 
{
  foreach($spweb in $spsite.AllWebs)
  {
    foreach($splist in $spweb.Lists) {
      if ($splist.Title -eq "NintexWorkflowHistory") {
        if ($splist.ItemCount -gt 2000) {
          $content = $spweb.URL + " * " + $splist.ItemCount
          $content
          add-content "NintexLists.txt" $content
        }
      }
    }
    $spweb.Dispose()
  }

  $spsite.Dispose()
}
"Total lists found: " + $total