Credit card holders are not liable for credit card fraud. The Electronic Funds Transfer Act protects account holders from unauthorized transfers for 60 days. The risk here is not so much credit cards as identity theft.
Idnar7, this situation sounds unusual because this is not the way Microsoft works, and there is a well documented scam that does work this way. It might not be a bad idea to wipe your system clean and use a recovery disk to reinstall Windows and all your software. Then change all the passwords for your accounts, especially financial and mail, and freeze your credit.
One thing you can do is look at the charge on your credit card to see the name of the business. There should also be location info. That might help confirm who accessed your computer, and it should certainly confirm if it was Microsoft or not.
Idnar7, this situation sounds unusual because this is not the way Microsoft works, and there is a well documented scam that does work this way. It might not be a bad idea to wipe your system clean and use a recovery disk to reinstall Windows and all your software. Then change all the passwords for your accounts, especially financial and mail, and freeze your credit.
One thing you can do is look at the charge on your credit card to see the name of the business. There should also be location info. That might help confirm who accessed your computer, and it should certainly confirm if it was Microsoft or not.