connection string for sqlexpress ,stumpted

[mikelynch]

I am getting "keyword not supported" for my connection string. I have tried to edit it a lot but getting nowhere.
Please help me with the connection string

using System.Data.SqlClient;
namespace Gymdata4
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            SqlConnection thisConnection = new SqlConnection( "Data Source=.\\SQLEXPRESS;AttachDbFilename=""+"C:\\Documents and Settings\\Michael\\My Documents\\GymData3.mdf""+"Integrated Security=True;Connect Timeout=30;User Instance=True");
            SqlDataAdapter thisAdapter = new SqlDataAdapter("SELECT * FROM customers", thisConnection);
            SqlCommandBuilder thisBuilder = new SqlCommandBuilder(thisAdapter);
            DataSet thisDataSet = new DataSet();
            thisAdapter.Fill(thisDataSet, "customers");
        }