1. Can a trojan horse be active and operating on your computer without your even knowing about it?

2. If so, how do you find out if you have a trojan horse?

3. Is it true, as I read somewhere, that an unsuspected trojan horse in your computer can discern your personal data, social security # if used (by counting keystrokes) and transmit this info back to the hacker?

I have Windows xp, Windows Defender, and Trend Micro all installed in my computer. None has identified a trojan horse infection.

RB