Disabling Checkout Button

I am using Google Checkout as my payment gateway, and therefore would like to disable the "Checkout" button on the shopping cart page.  Any thoughts on how to do this?

I actually figured this out by adding a Page_Load event to ordersummary.cs which checks to see if googlecheckout is the only payment method selected, and if so, hides the checkout button.

protected void Page_Load(object sender, EventArgs e)
        {

            //Hide then checkout button if "GoogleCheckout" in the only payment method enabled
            PaymentMethod googleCheckoutPaymentMethod = PaymentMethodManager.GetPaymentMethodBySystemKeyword("GoogleCheckout");
            PaymentMethodCollection aPaymentMethods = PaymentMethodManager.GetAllPaymentMethods();

            if (!googleCheckoutPaymentMethod.IsActive)
            {
                return;
            }

            foreach(PaymentMethod p in aPaymentMethods)
            {
                if(p.IsActive && p.SystemKeyword != "GoogleCheckout")
                {      
                    //need to show checkout button
                    this.btnCheckout.Visible = true;
                    return;
                }
            }
            //if we get here, then no payment method other than google is enabled, so disable the checkout button
            this.btnCheckout.Visible = false;

        }