Best Way to track user activity and changes?

Hi all, just got a theory question about tracking users. I want to be able to keep track of every change a user makes to the database. I can easily keep track of users making inserts in to the database, but then when they update it, it becomes a little trickier. Im trying to come up with a solution that is basically a function and can work for any change to any table.

What do you guys do for this? I was thinking maybe building an updates table like this

acct_id---table---field---original_value---new_value---date

But then the amount of updates going on this table can get fairly large. Any thoughts?

It is possible to use Checksum MySQL http:// adm-it. net/checksum-mysql