Java Eclipse JDBC ClassNotFoundException

I'm trying to connect to an external database and no matter what I do I keep getting the following error:

java.lang.ClassNotFoundException: com.microsoft.sqlserver.jdbc.SQLServerDriver
    at java.net.URLClassLoader.findClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Unknown Source)
    at DbCon.main(DbCon.java:10)

My code to set up the driver:

import java.sql.*;

public class DbCon {

    public static void main(String[] args) {

        try {
            Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
        } catch (ClassNotFoundException e1) {
            e1.printStackTrace();
        }
    }
}

I've tried omitting the driver entirely, and just trying to connect with:

String connectionUrl = "jdbc:sqlserver://xxx.xxx.xxx.xxx:1433;databaseName=xxxx;user=xxxx;password=xxxx;";
        try {
            Connection con = DriverManager.getConnection(connectionUrl);
        } catch (SQLException e) {
            e.printStackTrace();
        }

This only gets me the following error:

java.sql.SQLException: No suitable driver found for xxxx
    at java.sql.DriverManager.getConnection(Unknown Source)
    at java.sql.DriverManager.getConnection(Unknown Source)
    at DbCon.main(DbCon.java:15)

I've tried adding the jar to Eclipse's classpath, I've added the folder to the project's build path as an external class folder.

Is there something I'm missing?