I had a problem last March when someone in Russia hacked into my PayPal account and made three separate purchases that added up to around $400. Luckily I just happened to log into my bank account the next morning before I went to work and discovered it. I immediately filed a claim with PayPal and the charges were eventually reversed but it took about a week to for the money to be returned to my account. Turns out my password which I had thought to be pretty strong was not. An employee at my bank turned me on to password checker hosted by Microsoft that will tell you how strong your password is.

Here's a link: http://www.microsoft.com/protect/yourself/password/checker.mspx

Cheers!
Bill