Beginning users can barely get to their e-mail, intermediate users on the other hand are exploring, downloading, chatting online and beginning to make a lot of use of the powerful tool created by coupling your computer with a high-speed data service.  What would the expert users caution you about based on their experience?

1. Firewall - There are several varieties, but this is ultimately the first defense.  The firewall handles all incoming data before it has access to any application or information on your computer.  It also is the last thing to handle outgoing data.
• If you are using Microsoft Windows XP, you can ensure your firewall is enabled by going to Start Menu>Control Panel>Security Center.
• A firewall on your personal computer will block unsolicited attempts to connect to your computer and log the location of the computer that is trying to connect.  There are several free firewalls available on the internet.  Zone Labs provides free personal use of Zone Alarm as an example.
• If you use a router, switch, gateway, or other piece of hardware to connect to your high-speed data service (DSL, Cable, T1, etc.) then that hardware will likely have an additional firewall.  You will likely be able to log into the hardware with the computer that is attached to it using your internet browser window and an IP address.  Check the owner's manual of the hardware that connects you to the internet to see if there is a firewall included in your internet appliance and how to configure it.
  
2. Anti-Virus Software - Your computer probably came with this software, but have you been updating the virus definitions regularly?
• There are free anti-virus programs available, but given the importance of this feature, it is worth a few bucks a year to keep a paid subscription.  Some examples of free anti-virus programs are AVG and Avast!.  Both of these are free for personal use and have free updates.
• If your anti-virus software has an auto-update feature, make sure that is enabled.  Otherwise you will need to manually update definitions a couple of times per week.  On high-speed, this typically takes 30 seconds to complete.
• Quarantine infected files, let your anti-virus software decide what to do with what it finds (unless you are an advanced user).
• Make sure your anti-virus software has an "Always-On" feature which will scan in real-time.
3. Anti-Spyware Software
• You can get some great anti-spyware software for free; Microsoft Anti-Spyware Beta is a great real-time spyware program, SpyBot Search & Destroy.
• Heavy internet users should have a real-time program and then run a second one once or twice a week.
4. E-mail
• Do not open attachments unless you know the phone number of the person who is sending it to you.  This is so you can call them when they send you a worm or something and ask them to come over and fix your computer.
• Be extremely cautious about clicking links.  Even if the e-mail looks like it's from a major company, it could be a "spoof" with links that say the right web address, but send you to a not so nice site.
5. Keep all your software updated (patched)
• This is usually in a preference or option within the software to have it auto-update.
• When software companies identify vulnerabilities, they release a 'patch' to fix the vulnerability.  Although the patch may frequently have tweaking, it is released to prevent their customers from being exposed to an immenent threat.

Just to appeal to all the varying abilities out there, some additional PC security ideas are to backup your data by keeping data files on a separate partition than your operating system or having redundancy as provided through an additional harddrive and RAID setup.  Additionally, disabling Java, Javascript and ActiveX in both your internet browser and e-mail application will provide security.  Finally, configure windows to show all files and file extensions.  The impact of hidden file extensions is that you might receive a file that ends in .mpg which would appear as a music file, but actually ends in .mpg.exe with the .exe hidden, you would not know that opening this file will execute malicious code.  There are a small subset of file extensions that will remain hidden unless you remove all occurrences of the value "NeverShowExt" from the registry.

Feel free to contact me for additional information and resources on this topic.