Dealing with Trojans

"TROJAN" is the stealth nature and operationl practice of Spyware and Viruses.Parasite is what they all are.If you have a Trojan... nobody has just one! ...or two ...or three, etc. I usually find trojans that have been running on your machine for months. That's why they call them "Trojan".  You do not know they are there.

The most important thing you should know...
 is about how you get them.
I service several machines per week.  Most of my service activity is removing  Trojans and/or restoring the machine to normal function. Seldom do I find the older style infections that are from firewall penetration or email contents.  What I find is infection by: At least half of the infections I see are fraudulent claims that your machine is infected, and the user clicks "to remove the infection".  If you buy it, your machine will NOT be fixed by them. You will need me.Why is it that my Anti-Virus program does not remove them? I hope you have backed up your personal data   Backup your personal data before you bring your machine to me. It is extra cost if I have to do it.I Repeat!
Backup your personal data before you bring your machine to me. Why is this so important?
  1. You "pay yourself" less than you will pay me for performing data backup. 
  2. You know better than I do as to what is worth the extra time and space.
  3. My Virus/Trojan repair service is capped at (3) three hours, but data backup is a separate billed activity respective of how much data and how many users have their own user id.
Note: Emergency Data recovery cost per user.  That is different from "backup".Important!  Is there more than one User ID on your machine?  Each user is a separate backup.Defending yourself from Trojans
You are your best defender. Get smart about it.
Disclaimer: 
I do not have the time or interest to evaluate all the products and tools available. Once I have identified good products that help me with computer service and defending my own machines, I have no interest in doing more.

Link Comment Cost
Sunbelt VIPRE Consumer Reports praised and my favorite $30/yr
Grisoft AVGFree I really like this one. It is very good free or more
Avast Home Usually only techies know about this one free or more
Trend Micro They also offer a free scan online. see below $40/yr
Norton? Do not get this one. I will not work on a machine with it!  Sneaky.  
McAfee? Good, but over priced.  I will not use it. Overpriced

Browsers and E-Mail

Firefox browser is the best prevention you can have.  Use it!  Firefox has more useful user features than does MS Internet Explorer(but Microsoft is catching up).  Use the very good Firefox Help to learn about Firefox. It's good.

Tourist note:
Sea Monkey is: the Firefox browser and the Thunderbird email client packaged together (with some more tools you probably do not care about). Created by non-profit  Mozilla.org. Think of "Sea Monkey" as the newest Netscape-like entity.