If you've never passed a date as a parameter to a stored procedure while attempting to use the debugger in SQL Query Analyzer, you probably don't know that the date must be in a certain format (ain't nothin' but an ODBC thing) in order for things to work. If the date is not in the format [YYYY-MM-DD] or something similar (my new motto: dashes not slashes, or hyphens not... nothing really rhymes with hyphens), then you will get an error like this:
[Microsoft][ODBC SQL Server Driver]Invalid character value for cast specification