You can quickly calculate the potential cost savings you can achieve when you upgrade to Microsoft Exchange Server 2010. Enter basic information about your existing messaging environment and see your potential savings in specific areas of your business. You can modify the default values with your own estimates. Rest your mouse over the input areas for more details or to get help about how to use the calculator.

http://www.microsoft.com/exchange/en-us/exchange-calculator.aspx?WT.mc_id=soc-n-sa-loc-services-omers