Fastest way to check if a user is valid (C#, project server 2010 SDK, sharepoint server 2010)

Hi I am making an application where a PM would log in and be able to see their project, view weekly reports, and create new weekly status reports.

Right now this is what I am doing to check if the user is valid: basically ReadServerVersion() will raise a CommunicationException if the credentials are incorrect.

                adminClient.ClientCredentials.Windows.ClientCredential.Domain = domain;
                adminClient.ClientCredentials.Windows.ClientCredential.UserName = username;
                adminClient.ClientCredentials.Windows.ClientCredential.Password = password;
                adminClient.ReadServerVersion();

Does anyone know of a faster way to check if the user is valid using WCF? I am staying away from anything asmx such as the login() method.

Thanks!