I made a paypal for each region I want and just send it money from my NZ paypal, standard crap international paypal rates and I pay a little fee, but once its in the other paypal account it spends fine on the xbox/whatever stores.

Not done the comparison against those aweful prepaid credit cards like the loaded for travel or the air NZ one, but I would be suprised if there was much in it, and not having my cash locked up in a prepaid card is worth a bit more anyway.