Ubuntu Security :: Programs Running Among Ubuntu Build To Assure Secure Transaction

yesterday I ordered some software on the Net.Early this morning, I got a call from my bank someone else tried to charge to my debit card.I called the company I ordered from to alert them and they assured me it had to be my computer security because theirs was checked, upgraded regularly and above reproach.Fortunately, the bank caught it in time and my account wasn't debited. After I assured them I didn't order anything from Bed, Bath and Beyond, the bank shut down my card and I had to apply for another.

I was shocked. You hear about it but never imagine it will happen to you. I began to wonder and worry if it was because I was using Linux and it wasn't as secure as Microsoft.I'm isolated in a very small town in West Texas so I order some things on the Net.I loaded the full version of Ubuntu "Lucid Lynx" 10.04 from a 4 disk set and downloaded all the upgrades; almost five hundred and set everything up the way I wanted. My question is: Are there programs running among the Ubuntu build to assure a secure transaction on the net or do I have to load others and a fire wall like Windows? That's one of the reasons I left Microsoft behind was the "Auntie-viral" programs took over and almost became a competing system.