Thanks! So I assume I would need to use the SQL Server Config Manager to specify what port each instance uses correct (looks like there is a how to article in the SQL 2008 Books Online library)? And if so then I should be able to use the server IP and port# with my app (it is a .NET-based app) instead of servername\instancename and can then turn the SQL Browser off (maybe)? Then use the policies to restrict inbound traffic per web/app server to each SQL instance port - correct?

Sorry if I sound like an idiot but at least I admit when I need to go to someone else for answers. Thanks for the help!!