I've gone through the basic setup and placed the code into my page header. For some reason, though, I cannot see the cart spawning a popup window to show the cart. Instead, it takes me offsite to a plain white skinned cart.
I know I haven't provided a theme yet for the checkout, but honestly, I haven't even selected the "Checkout" button yet. It shouldn't be in that part of the process yet.
I recall all the demo carts using this method and am wondering what I might be doing wrong. Thanks to all for your help.