Vista - Answer the design questions three!!!

I am designing my web based interface! I created three layers, the GUI
layer, the Business layer, and the Data layer. I store the data being
transfered back and forth from the gui and into the database into a class.
This class is more or less a cache of the gui and used to populate the
database table and vis versa. The code to do that is in the data layer.
Now, I am thinking that I should instead use a System.Data.DataRow (as
captured on the query). In the new way, any changes made to the table are
immediately accessible elsewhere. Is the first approach the industry
standard for dealing with this issue? Unfortunately, this new approach
doesn't do much for my architectual design of separting the data structures
and blows a big hole into the whole 3 tiered architecture.

Does anyone have any links to good talks with examples of the best way to
solve this issue?

Is it worth the effort to change all my previous code?
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My appologies to Monty Python