Concatenate

Hi,

I need to create a concatenated field in SQL 2008.  In my DB table, I have a field called skidnumber.  This is a numeric field with sequential values (1, 2, 3, 4, etc.).  I need to create a field that is 9 characters long.  The first 3 characters of the field must always be SPA and then the following characters will be the numeric values from the skid number field.  Example: SPA000001, SPA000002, SPA000003, ETC. 

How can I create this field and always have it be a total of 9 characters long? 

Thanks!