Can II use shipping director to display a message.

Is there a way to display an alert box that can inform customer that a "certain shipping method" is available? By default, I have fixed rate shipping methods. When customer adds more than $100 in their cart, the option to ship via UPS is available. I want to alert users that this is available.

Shipping Director can control which methods display on the "shipping method selection" page.  Additionally, on that page, "error" messages can appear that would prevent the checkout from continuing.  SD cannot display messages on the "shopping cart" page.

Thanks New York, I sent you a PM.

I understand your response in saying that SD can't display a message on the cart page, but is it able to display a Notice Message on the checkout page along with the shipping options, but not prevent the customer from checking out or seeing the available shipping options?

No.  The messages are returned to the core nopCommerce as 'errors', so it won't display the options, and it prevents the checkout from continuing.  There are "HTML Widget" plugins that can be used to display text in widget zones (e.g. "op_checkout_shipping_method_top"), but I don't think those plugins support 'conditional messages'.  nopTools has considered building a Checkout Director ;) with such features.  Contact us at support at nopTools dot com, with your thoughts.