If I have a stored proc in SQL Server 2008, I know I can run it from management studio like so:
exec rpt_myproc @include_all = 1, @start_date = \'1/1/2010\'
Are you sure it is a sproc? I've never heard or seen a usage of doing a direct select from a sproc.
What I have seen that works and functions exactly as your code seems to be working is table-valued functions, which are functions, that can take parameters and return a "SELECT FROMable" table just like this (in essence giving you a 'parameterized' view).