Audit Data

Hi all,
I would just like to ask whats the best way to make some audit on some of the tables in a MS SQL server, what i'm planning to have is to have a table which can contain all changes/inserts/deletion of some given tables, my first idea was to have this:

AuditTable that have the following fields:
AuditID, TableName, FieldName, OldValue, NewValue, UpdateBy, UpdateDate

then in all the given tables, i'll have insert, update and delete trigger, the issue comes down to the trigger, what will be the best way to have that trigger written in a way that it can be use for other tables as well? say if a table have more then 20 fields, I don't want to declare 20 var and compare them 1 by1, and if there is a diff, then i insert to the audittable, I want something that it can loop and (if possible) be able to use by other table as well, so the field name etc can get from sysobjects, but then how can you code it in a way that it can do that?

Or is there any better way to get the same result? currently i have an audit table for each table i want to audit on and its just wasting space, any help will be great.
Thanks,