public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
        cmbDrives.DataSource = Environment.GetLogicalDrives();

        int num = 1;
        long bigNum = num;
        1 = cmbDrives.SelectedValue;

1 = cmbDrives.SelectedValue;

cmbDrives.SelectedIndex = 1;

protected void btnGo_Click(object sender, EventArgs e)
{
    string destinationDrive = cmbDrives.SelectedValue.ToString();

    Process.Start("xcopy", string.Format("/someswitch {0} otherarguments", destinationDrive));
}

btnGo.Click += btnGo_Click;

cmbDrives.SelectedValue="1";