SQL Server query to find all permissions/access for all users in a database

I would like to write a query on a sql 2008 that will report all the users that have access to a specific database, or objects within the database such as tables, views, and stored procedures, either directly or due to roles, etc. This report would be used for security auditing purposes. Not sure if anyone has a query that will fit my needs completely, but hopefully something that will give me a good start. Either sql 2008, 2005 or 2000 will do, I can probably convert as needed.