Use Excel Macros to compare that. It is embeded in the Excel.. Performance wise its too fast... Incase you need to integrate with ur existing QTP script, use QTP script to invoke macro and get the status back to mark the completion of macro.. Hope you got it....
An alternative would be to use Microsoft Access. I am not sure how familiar you are with Access VBA. You have the the ability to import the Excel tables into Access and then use the Query-By-Example within Access to run queries. Not sure what type of comparisons you need to perform but Access has some predefined queries and a query wizard to help out.
Can you share a little bit more on the rules you want to use for the comparison? If you discover a difference between a cell value in your comparison, does the Excel processing stop? What other rules are there?
Here is a code sample of setting up Excel Automation. I original wrote this for VBA. I pulled out the strong variable typing so it should work for VBScript.
' This does NOT display the formula, only the contents of the cell!
' Debug.Print "The formula property in cell 'A1' says: " & objActiveSheet.Range("A1").Formula
' Debug.Print "The formula property in cell 'A4' says: " & objActiveSheet.Range("A4").Formula
' This DOES display the formula. Notice the EQUAL sign!
' Debug.Print "The formula property in cell 'A6' says: " & objActiveSheet.Range("A6").Formula
Set objActiveSheet = Nothing
Set objWorkbook = Nothing
Set objExcel = Nothing