LOG table changes ...

hi,

I want to track every change made to several tables...and was wondering
what is the best way... What are my thoughts at the moment are to make a
table like this :

id, table_name, field_name, old_value, new_value, timestamp

and triggers to do the logging.
but this will probably generate alot of traffic (not so worrying at the moment)

As I side effect of this I want to be able to make a snapshot of the TABLE at specified time..
any ideas on this too...

tia.

P.S. Other way would be to make a duplicate table and transffer the whole record, but
dont think this is a good solution