How to split workbook into multiple workbooks based on date range

Hi there,

I have a workbook that contains c.480,000 rows of data which i need to split into multiple workbooks based on a criteria.

Column a = product name
Column b = date (dd/mm/yyy)
Column c = time (in 15 min intervals)
Colum d = sales volume

There is a row for each product for every 15 minute interval for each day of the month (2972 for Jan 2012)

There are 151 unique products in total hence the number of rows.

What i'm after is a macro to copy each product type into a seperate workbook therefore ending up with a workbook for each product.

Please see attached sample file...