Well, I wouldn't worry about tasks or anything. It's going to take a bit more in the way of communication ("Hey, I'm checking something in!"). In any case, best practice is to not run your tests on the same set of files as you are developing on. Your regular test runs should have a copy of your test projects that are only updated one way (TFS -> Test environment) rather than actually developing against your test environment. Consider what would happen if a developer was developing a web application on your live server that folks were actually using in real time... yeah, not a good practice there. :)