Things may be slightly different depending on whether you are using the most recent version of wp e-commerce (I think its 3.8 something) – but it’s similar in 3.7
In the shipping settings you can choose Flat Rate and then hit edit and set the shipping rates for continental US as well as other continents.
Table rate refers to specific shipping rates related to a certain product, rather than its destination.
There’s also a new(ish) plug in for setting other various fixed rates of shipping that you can find ->> http://wordpress.org/extend/plugins/wp-e-commerce-fixed-rate-shipping/
Hope this helps you some