Ok, as usually it happens - the moment I posted the previous message I made it work. Had to change the code (changed "Jet" to "ACE" and moved the single quote after HDR=Yes' ). Something like this for my purpose would fit perfect - extract all cell values which are negative in a given worksheet in a given range:

 Code:
$adOpenStatic = 3
$adLockOptimistic = 3
$adCmdText = &0001

$objConnection = CreateObject("ADODB.Connection")
$objRecordSet = CreateObject("ADODB.Recordset")

$objConnection.Open("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\Temp\Merger.xls;Extended Properties='Excel 12.0;HDR=Yes'")

$objRecordset.Open("Select Number FROM [Sheet1$A1:B20] WHERE Number < 0", $objConnection, $adOpenStatic, $adLockOptimistic, $adCmdText)

While NOT $objRecordset.EOF
  ? $objRecordset.Fields.Item("Number").Value
  $objRecordset.MoveNext
Loop