The vendor is probably as much of a victim as you are. ID thieves don't target individual accounts because it's too time consuming. Instead, they go after vendors and gateway services who haven't spent the necessary time and effort to protect customer data from determined thieves.
See if your bank offers a prepaid card service, preferably one that allows you to transfer funds to it online. Many larger banks do--I'm using one to make sure my college age daughters have gas money and I don't transfer anything more than the cost of a tank of gas and a can of Red Bull. If they lose the card or if it gets compromised, I'll toss it and get a new one.
Also, don't think PayPal is safer than using a bank or credit card. A client of mine had thousands wiped out last summer when he used PayPal to pay for equipment and supplies from overseas. To date, PayPal has still not made him whole.
Edit to add: It makes sense to make sure your PC is as secure as possible. Never, ever, EVER us MS Internet Explorer for online shopping. In case you missed it--never, ever, EVER. Use FireFox or Google Chrome, both of which are light years ahead of MSIE.
Get yourself a good antivirus/malware protection application. There are many good ones that are absolutely free for personal use and are as good or better than Norton or Symantec. Norton is better than nothing, but not much better. Symantec is better than Norton. My favorite is LavaSoft's AdAware. It's free for download and free for personal use, with a reasonably priced upgrade to additional features.