There are very many ways that one can hack a computer, and if you are just trying to secure against trojans than your leaving yourself open for a variety of other attacks. I might be just my opion but to me trojans are old school and are used by people with no talent. You need to get a firewall (hardware prefferably). You also need to monitor the traffic coming out of your pc to detect if you have already been attacked. Anyways thats just my advice.