Tracking data changes in Database

Hi,

I am working on a project where large amounts of data is created and updated on a regular basis. I am using SQL Server 2008 as the database. All is well and the project is working fine. But the client needs all the changes and updates that are done by the users of different departments in tables. I planned of doing it using Triggers, but i think that it will affect the performance of the system. And this data is to be displayed on an asp.net C# web application for the Admin to monitor. Please suggest me what method i should use to achieve the task. 

Thanks and Regards,

Chandra Sekhar T