Date Returns

Does anyone know if the date function returns false if it cannot convert the specified date/time to the format? If not, does anyone have a rule set they use to verify the date is a valid convertible date? I need to update a row in MSSQL, and it will fail if the date is incorrect. I've validated for the basic things, but just am not sure what the best way would be to validate the actual date itself. I was thinking of RegExp, but not certain if that would really work for multiple date formats for example: March 15, 2002 03/15/2002 3/15/2002 and so on and so forth. The field actually requests a dd/mm/yy format, but you know how people follow instructions. Thanks guys, Ryan