APEX

I've got an application which currently tracks changes on a very high level - really just user ID, date/time, project ID changed and what the action was (deleted, updated, added, assigned). Is there a nice easy to use process in Apex that I can adapt to determine what fields may have been modified for this audit log?

For instance, I have over 100 fields for the project tracking portion of the application, however someone may just update one field (a due date for some portion of the project, for instance) while leaving all other fields alone. Currently I just see something like:

John Doe updated Project ID 125251 @ 12:45pm on 10/23/09

However, I'd prefer to see something like:

John Doe updated Project ID 125251 @ 12:45pm on 10/23/09. Test file due date is now 11/2/09, was 10/29/09.

I've done a quick search or three looking for this functionality and haven't found much, so either I'm using the wrong terminology (very possible) or this isn't something that exists in APEX (also likely). So I reach out to all of you.

Thanks!