In your proc GetProcessorUsage, you're referring to a column 'cpu_ticks_in_ms' which doesn't exist in sys.dm_os_sys_info in SQL 2008 - http://msdn.microsoft.com/en-us/library/ms175048.aspx

According to this article, the column has been removed from post-SQL 2005, and provides a solution of sorts - http://connect.microsoft.com/SQLServer/feedback/details/292638/katmai-give-us-back-the-cpu-ticks-in-ms-column-in-sys-dm-os-sys-info

HTH.

Mike