Ideas to Update DATA received from the client

Question

I have not big DB (12 tables) Suppose application is requested for some data about specified clientID by means of ADO.NET i got all the relevant data about this clientID from several tables to the client, client perform tasks on this data change it maybe add something new or delete somtething (there is posibility that data will not changed at all), after this client click to SAVE button and return data to DB, here start the problem, i can delete all relevant data about specified clientID in all table and after this insert data tables (insert data that recieved from the application) or i can check what changed and to remove or update or insert data. ANY IDEAS, and maybe how to perform my problem. I'm using: Windows Xp, .NET Framework, Sql-Server 2000.