There are several ways to store the output in excel.
The two easiest are
1. In query Analyzer set your Output to File and your ouput format to CSV (Tools->Options->Results will create a file you can open in Excel
2. Even easier is to set the output to Text and output format to Tab then select your output and paste into an open excel worksheet.
Other methods include writing an excel macro to connect to the SQL Server and execute the stored procedure - you can use the ADO connection, command and Recordset objects.