11 steps to secure your pc

  1. Choose an operating system based on its security and vulnerability (Linux has no known active viruses in the wild, OpenBSD is focused on security). Find out if it uses limited user accounts, file permissions and is regularly updated. Make sure you update your operating system with security updates and update your other software too.
  2. Choose a web browser based on its security and vulnerabilities because most malware will come through via your web browser. Disable scripts too (NoScript, Privoxy and Proxomitron can do this). Look at what independent computer security analysts (such as US-CERT) and crackers (similar to hackers) say.
  3. When setting up, use strong passwords in your user account, router account etc. Hackers may use dictionary attacks and brute force attacks.
  4. When downloading software (including antivirus software), get it from a trusted source (softpedia, download, snapfiles, tucows, fileplanet, betanews, sourceforge) or your repository if you are using Linux.
  5. Install good antivirus software (particularly if you use P2P). Antivirus software is designed to deal with modern malware including viruses, trojans, keyloggers, rootkits, and worms. Find out if your antivirus offers real-time scanning, on-access or on-demand. Also find out if it is heuristic. Avast and AVG are very good free editions. Choose one, download and install it and scan regularly. Keep your virus definitions up to date by updating regularly. Protect your computer from external networks  using a good firewall and antivirus solution
  6. Download and install software to deal with spyware such as Spybot Search and Destroy, HijackThis or Ad-aware and scan regularly. I can’t state this enough – you need to run a good anti spyware and anti malware program like Spybot if you search the web at all. Many websites out there exploit weaknesses and holes in the security of Microsoft Explorer and will place malicious code on your computer without you knowing about it until its too late!
  7. Download and install a firewall. Either ZoneAlarm or Comodo Firewall (Kerio, WinRoute or Linux comes with iptables). If you use a router, this gives an added layer of security by acting as a hardware firewall.
  8. Close all ports. Hackers use port scanning (Ubuntu Linux has all ports closed by default).
  9. Perform Penetration Testing. Start with ping, then run a simple nmap scan. Backtrack Linux will also be useful.
  10. Consider running intrusion detection software (HIDS) such as ossec, tripwire or rkhunter.
  11. Don’t forget to think in terms of physical security (in case of theft/unauthorised access), like setting a BIOS password and preventing access to your machine or its removable devices (USB, CD drive etc.). Don’t use an external hard drive or USB device for important data, these represent another vulnerability, as they are easier to steal/lose. 

Article Source – WIKIHOW