Password protect all the User Account of your windows PC. It is good to disable Guest Account. In Windows XP Home Edition disabling the Guest account is not possible. So set a strong password fot it instead. Guest account is used by Windows for file and folder sharing. Another computer in the same network can access your shared folder without any authentication if User Account is not password protected. So always password protect all the User Account.

Always install latest patches from Windows update. Always download latest updates and install it. These updates includes security updates, IE updates etc. Unpatched machines are frequently exploited within minutes of being attached to an open network. Be sure you've installed all the updates for Internet Explorer, too. IE is an integral part of the Windows operating system, and must be patched at the same time other security fixes are applied.

Always disable unnecessary applications and network services. Make sure you disable Alerter, ClipBook, HP Web Jetadmin, Netmeeting, Remote Desktop Sharing, Network Dynamic Data Exchange, Network DDE DSDM, Remote Registry Service, Routing and Remote Access, telnet, and Universal Plug and Play Device Host, if they are enabled.

To protect your PC from worms, Virus and torjons, always install antivirus softwares. To get latest virus definations, update your antivirus daily to keep it up-to date. Scan your computer once in a week. While using removable devices line pen drive, scan it before opening it.

Windows XP includes a feature, the Internet Connection Firewall(ICF). The ICF restricts access to services running on your machine, so it can prevent many kinds of attacks. ICF only monitor and block inbound traffic. So we recommend you to use third party firewalls like Zone Alarm, Outpost Firewall. There third party firewall monitors both inbound and outbound traffic. If you don't want to use third party firewall, atleast turn on builtin Windows Firewall.

Donot open any email attachments unless you are sure about it's origin. It may contain malicious program or virus. Before opening it, download it and scan it with antivirus.

Always take a backup of your critical data in removable drives like CD, Zip drive etc. So that even if your PC gets infected with virus, you can recover your work.

If you want to share files and folders between few computers in a network, put a unique workgroup name. WORKGROUP is a default workgroup name in Windows. Only share necessary files and folders. Donot give full acess (write acess) to your folder while sharing.

Close vunerable ports like DCOM RPC(port 135), RPC Locator(port 445), NetBIOS(ports 137/138/139), UPNP(port 5000) for security reasons.

When your PC is not in use, turn off or disconnect the internet for safety reason.