I am putting this link in - as a reference for anyone who wants to get the arduino to send data to an Excel spreadsheet.
http://dev.emcelettronica.com/serial-port-communication-excel-vba
please pay particular attention to the one line of the code that needs to be modified if your serial port number is greater then COM4 - i didnt, and struggled !
I have recently started using this myself to get the outputs from 4 thermocouples - upto 1100 degC ( via a Ryan j Mclaughlin arduino shield ) - got great graphs now !