I am building a Sharepoint web part that will be used by all users. The web part connects to a web service which needs credentials with higher privileges than common users. I hard coded credentials in the web part's code.

query.Credentials = new System.Net.NetworkCredential("username", "password", "domain");

query is an instance of the web service class

This may not be a good approach. In regard with security, source code of the web apart is available to people who are not allowed to see the credential. This is bad enough, But is there any other drawback of this approach?

How to prevent hard coding credentials into the source code?

Thanks