Converting Dates to Numbers

[Panda2000]

I have a list of shipping dates and I am using them to calculate cycle times. In the past we have been simply subtracting shipped date from received date to calculate the shipping time but now management wants for the weekends to be excluded from this calculation. So what I would like some help with is to take this list of dates and number it sequentially in a new column. For example if the first date shipped for the month is 6/1/2012, then that row would receive a value of 1 in a new column. The next shipped date is 6/4/2012 so those rows would receive a 2 in a new column. This way I will be able to calculate the shipped dates excluding the weekends. I will also include the received date so that if anyone thinks of a better method please feel free to suggest so. Also, a shipped date will never fall on a weekend. Thank you very much for your help.