Unfortunately you need a US registered credit card to buy from the Sony store, you can buy multiformat books from
www.fictionwise.com and download as LRF files (the PRS 500s native format), or convert from MS Reader files (unprotected) to LRF using a very handy program called calibre, I actually use that instead of the standard sony desktop software, if you have any more questions, there are loads of people here who'll answer, usually with lots of different answers
