I've used tor quite a bit, from firefox webbrowsing to even making my trillian communicator run through the proxy.

As far as I've seen, it's incredibly reliable and secure. DNS information may leak out once in a while if you only give an IP rather than the server name, but that's not something most people are going to be able to sniff out. Since you are tunneling through multiple other proxies on the onion network, tracing you back involves more than just one trail.

The reason sygate detects you have a trojan is because it is scanning the tor server you are running, NOT you. That "trojan" is most likely the tor server they are running. Christ... I hate that sysgate scanner so much.