Sorry to hear your loss, I would get the CC on alert at least and changed if it doesn't include other problems like automactic bill pay.
IE is your first mistake, a hack waiting to happen. Using one computer is always a problem, but you can prevent some things like keyloggers if you out smart them. Try a virtual machine and do not use that for WOW. Try linux. A live CD will stop some of the baddies. Get a netbook and use that for all but WOW.