Kemp Technologies has released a sizing guide (still in beta) for Exchange 2010, which compares the different load balancers they sell, depending upon our input. It is pretty much like the Microsoft Storage Calculator, except that the tool is only interested in parameters that affect the selection of a load balancer.
Depending upon the input given, the tool lists the load balancers that will meet the requirements.
Pretty good tool, check it out here
--> A voir sur le site : http://www.howexchangeworks.com/2011/06/kemp-technologies-load-master-sizing.html