Strategies for testing multi-user desktop application

Question

Hi,

We are developing a multi-user desktop application with C# 3.5, windows forms and sql 2008. There are various things I want to test - 1) performance - how application behaves when multiple users are accessing the database? 2) How to simulate a conflict, and test how application is helping out the user. How can I test the above scenarios?

Any other scenarios you can think of?

thanks