How to automatically execute a stored procedure every day at a particular time?
If you are not comfortable using Powershell, then you can go for native service broker functionality.


This might sound complex, but below links has all the scripts :

Scheduling Jobs in SQL Server Express - Part 1 and

Scheduling Jobs in SQL Server Express - Part 2
Alternatively, you can use Standalone SQL Agent - still in BETA statge from codeplex.
You can use the native sqlcmd functionality and then schedule it using windows scheduler or Schtasks

sqlcmd -E -S server_name -d database_name -Q "EXEC schema_name.StoredProcedureName @p1"