I recently found, via Google searches, and implemented successfully, a trigger based solution called AutoAudit (http://autoaudit.codeplex.com/). This is an open source project, which auto generates triggers on your base tables. On DML operations the triggers fire and populate a few consolidated tables that store the old and new records and details of the change. Being open source it was free, and it has been really good in so much as we've never had a problem with it and it passed all our tests. Because it was open source we tested it exhaustively prior to implementation.

The DB where we've installed has low data volumes, and pretty low growth. Our DBA did say that if we had high data growth, due to the consolidated tables, he perhaps wouldn't have allowed it.

I recommend you give it a look.