PC Goes Tingi! (Paid By-The-Hour Courtesy of Microsoft)

According to USA Today, Microsoft has developed the technology for people to pay for their computer "by the hour" through the use of "prepaid cards". Called "FlexGO", it goes something like this: A prospective buyer gets a computer and pays half of its price at the store. Then he buys a "prepaid card" and works/plays on the computer based on the number of hours paid for in the card. The computer connects to a server and logs the number of hours used in the computer and adds up the money spent for the prepaid card to the amount that needs to be paid for by the owner. If the value of the "prepaid card" is exhausted, the computer stops working.

This sounds good in principle but making it to actually work would be an administrative nightmare for Microsoft. What would prevent tech savvy users from circumventing the system? How hard (or rather easy) is it to create counterfeit prepaid cards? What will prevent the owners from removing Microsoft from the computer and installing other OS (read: Linux) on it to avoid paying for the balance of the computer?