I'd actually recommend that you use windows authentication wherever possible for the following reasons:

1. You will immediately know who is accessing your data - with SQL Authentication, it's not always immediately clear who is looking at your data.

2. It eliminates any chance of you needing to know a users password.

I agree with the posts here stating you should never need to know a users password. Windows authentication stops this ever being a problem for user logins. I do store all my Application SQL Logins however.