Here are a few things that I recommend for folks who use PC’s … think of them as “David’s Rules for PC Owners” …

1. Backup the hard drive on your computer.  Hard drives are mechanical devices.  They break.  If you don’t want to loose all those photos, videos, letters, etc, then you absolutely MUST back up on a regular basis.  You should buy a big external USB (or Firewire) hard drive (at least 3 times the size of your computers hard drive) and backup software (I recommend Norton Ghost).  Setup the software to periodically backup your computer to the external drive.  It should do some kind of backup (either full or incremental) at least once a day.  Then, if when you hard drive fails, you can restore from the last backup using the CD provided.
2. Stay current with your Anti-Virus software.  So many people buy a computer with anti-virus software installed, but don’t keep their subscription for virus signatures up to date.  When the software warns you that your subscription is about to expire, RENEW.  If you don’t have current signatures, then you are vulnerable.  Even the most careful person sometimes makes a mistake.  Virus signature subscriptions are not that expensive and can save you a boat load of trouble later.
3. Get your own internet domain.  There is nothing more annoying than having to tell all your online contacts that your email address has changed.  If you get a domain and email service, then your email address will never change.  Personally, I suggest getting the domain from GoDaddy and email from Google Apps for Domains (you can also register a domain through Google, but I find it more useful to use GoDaddy).  You also get chat, calendar, word processing, presentation, etc, with Google Apps.  Google’s email (which is based on Gmail) has very solid anti-spam protection.
4. When purchasing a new computer … DO NOT opt to have the install media provided computers hard drive.  If your drive fails and, for whatever reason, you are unable to recover it … you have no way to reinstall the operating system.  Always get the install media on CD or DVD.  There may be a charge for the media (which is stupid, but reality), but spend the few extra bucks.
5. Never connect your computer directly to the modem (cable or DSL) provided by your ISP.  Always, even if you just have one computer, buy a router to connect to your modem.  This provides an incredible amount of protection, as your computer is not directly attached to the internet.  If someone decides to attack your IP address, they just pound on your router and never touch your computer.  Most routers also have wireless built in, so you get that advantage too.  I suggest Linksys routers.  They are easy to use and quite robust.
6. If you use wireless on your router, enable password protection.  At least use WPA, if not WPA2.  If you don’t turn on password protection, then all the resources on your network are fair game.

These few things can make your PC usage a lot easier in the long run.