AVG is a great anti-virus program, and it's free for personal use. Just use google or whatever search engine you prefer and search for "AVG Free" to get it. I use it and I only get a few security problems now and again (including one really horrendous bug about a week ago). Anyway, a lot of anti-spyware programs can detect trojans and worms, too. Spybot S&D, Ad-Aware, Spysubtract, and Windows Defender are all great at hunting down and systematically irradicating harmful pests in your computer... and all of them are free, too. But be warned: Windows Defender is, like every other Windows application, a serious resource hog that refuses to close when you ctrl-alt-delete. But here's my tips for avoiding trojans, worms, adware, spyware, and malware:
1. Don't steal. Some people are idiots, and those idiots put "song" files and "movie" files on the net that are infested with viruses. It's happened to me, and since then I haven't been a cheapskate and I've actually bought all the music I listen to or the movies I watch
2. Don't open e-mails from people you don't know. That should be obvious I'd hope. Also, don't open any e-mail that has a file attached to it, even if it's from a close personal friend, unless you already knew that attached file was being sent. If a friend sends one and you weren't expecting it, email him or her and ask if they intended to attach a file.
3. Don't send or read forwarded e-mails. This has nothing to do with viruses... they're just obnoxious and I want to try and bring them to an end!
4. Don't look at pornographic sites without a pop-up blocker. Some people laugh, and others need an explanation. Some prOn sites use ActiveX to try and sneak stuff onto your hard drive and some really ugly viruses can manifest that way. Most people who visit naughty sites are smart enough not to accept downloads or grant access when prompted, but others aren't that bright
5. Don't download anything from any websites that don't appear to be trustworthy. That's a given, but some people need to be told... I'm not saying you're dumb or anything, but if someone who IS dumb finds this thread, that tidbit might actually teach them something
edit: While I don't agree with Drew's methods (ever, lol), I'm sort of agreeing with him in that Flappy, as a mod, should have been a little less dramatic and a little more helpful. But that's just my opinion.
I haven't had a virus infect my computer that was bad enough to warrant a hard drive format since Windows 98 was still cool
"In an interstellar burst, I'm back to save the universe"