People be careful with your dealings over the net there are quite a few overseas networks tapping into hijacked computers and stealing all kinds of information before you know it and you would not know it.
The software planted replicates windows files so it is very hard to detect then it opens a backdoor mimicking a windows process and then any personal info is at risk or stolen.
I know I had one few months back and took me three full days to get rid of a nasty one. In priciple I would remove and then kill the system and hard drive so it was a real pain to remove. This particular one came from Shanghai(China) but also very active ones are in Russia, Baltic states, Ukraine and South America (from here I was offered Australian visa card numbers once).
Strangely enough a few days ago I went to a floor tile page and a trojan loaded from there I immediately written to the manager and I was told they did not know until they alerted the sysadmin guy.
To prevent such attacks an antivirus is the first line of defense followed by a firewall (rather more complex to configure properly) or firewall router.
So it pays to check from time to time your computer processes, packets and protocols.