The spreadsheet I used was adapted from a Vertex42 spreadsheet. Vertex42 is a leading provider of Spreadsheet Templates for Microsoft Excel, OpenOffice.org , and Google Docs. To browse through the Vertex42 collection please visit this link: www.launchexcel.com/vertex42-youtube
Please bear in mind that this is an affiliate link so I will make some commission if you buy from the Vertex42 website. There's also a nice range of FREE templates that are well worth downloading too - enjoy!