If you have to be that confident in your computer security to use the payment system, it's not going to have many clients.
Maybe the trusted computing platform (palladium) may have something to offer after all, namely enabling naive users to use services that require confidence in their own security. One could argue it's like going to a Vegas casino; software vendors (MS *cough* MS) probably won't cheat you in such a system because they don't have to; the odds are in their favor already. The whole system is designed to assure they get paid, and they have a lot to lose (confidence in the platform) by cheating you (at least in ways that can be detected). And since you won't be able to do anything to compromise the security, you can't screw it up. While I wouldn't see an advantage in that, I might recommend it for my grandmother. More on topic, I recently heard about a scam involving differential reversibility between two remote payment systems. The fraudster sends you an email asking you to make a Western Union payment to a third party, and deposits the requested amount plus a bonus for you using paypal. The victim makes the irreversible payment using Western Union, and later finds out the credit card used to make the paypal payment was stolen when paypal reverses the transaction, leaving the victim short. -- http://www.lightconsulting.com/~travis/ -><- "We already have enough fast, insecure systems." -- Schneier & Ferguson GPG fingerprint: 50A1 15C5 A9DE 23B9 ED98 C93E 38E9 204A 94C2 641B