Basic Security 101
Basic security stuff is not complicated, but it does take effort and a certain amount of vigilance on the part of every computer user.
Remember the five basics for security and always practice them.
Basic # 1. Always use a firewall. Most Windows computers these days come with the firewall turned on. While many computer experts feel that the Windows firewall is not all it should be, it will keep most hackers at bay. There are a number of third party firewalls and some are free. Don't disable your firewall for troubleshooting and forget to turn it back on!
Basic # 2. Always use an updated virus scanner. There really is no excuse not to use a virus scanner. There are a number of free and effective virus scanners. If you don't have one, get one, now!
Basic # 3. Use a spyware scanner. Better yet, use several. Keep one running in the background if possible and use the others weekly with manual scanning.
Basic # 4. Patch, patch, patch! Keep Windows updated. Keep all third party software like Flash, browsers like Firefox, your IM and other popular programs updated. Use a service like Secunia to keep tabs on third party programs that need updating. Secunia is free so there is no excuse not to use the service.
Basic # 5. This is probably the most effective basic, use common sense!
Common sense means you must not click on links if you don't know where the link will take you. This includes links in email from friends and strangers. (You really shouldn't even open email from strangers.) Don't use file sharing programs like Limewire to download music or software. These files are coming from who knows where and can contain virus, worms, Trojans and spyware.
The biggest threat to your computer may just sit in the chair in front of your monitor. You must learn to recognize a 'phish and to use restraint about clicking links!
With the advent of social networking sites also comes the bad guys trying to lure unsuspecting users. All those tempting games, fun stuff, etc., means new opportunities for malware to be implemented. Be very careful before clicking to 'join' a new game! And remember, clicking links in Facebook can also lead to malware.
Google has provided a great resource for staying safe online.