4. Use A Free Firewall
It's this simple -- you need a firewall. It's one of the best ways to protect yourself against Trojans, to keep your PC from becoming a zombie that obeys the commands of a distant hacker, and to stop attackers from worming their way into your PC.

If you have Windows XP Service Pack 2, you have a halfway useful firewall built in. (If you haven't installed SP2, immediately upgrade by going to Windows Update.)

By default, when you install SP2, the firewall is turned on. But if you suspect it's accidentally been turned off, you can check by clicking the Security Center icon in the system tray. The Security Center screen will pop up. (If the Security Center icon doesn't appear in your system tray or Taskbar, select Control Panel > Security Center.) Look at the top of the screen to make sure the firewall is turned on. If it's not, click the Windows Firewall icon at the bottom of the screen, select On, and click OK. The firewall will now be turned on.

At the very least, make sure to turn on Windows XP's firewall. Click image to enlarge.

But the firewall built into XP only offers inbound protection -- in other words, it blocks unsolicited incoming connections, but not outbound connections. Spyware and Trojans often "phone home," making outbound connections from your PC without your knowledge. If you want to block outbound connections, you need a two-way firewall. The best free one you can find is ZoneAlarm from Zone Labs. If you're only looking for a two-way firewall, there's no need to buy one of ZoneAlarm's for-pay versions, which offer extra features such as virus protection.

This is one area where users of older versions of Windows don't have much in the way of free options. ZoneAlarm no longer supports Windows 98 and ME, so if you're using one of those operating systems, you'll need to shell out for a commercial firewall such as Symantec's Norton Personal Firewall or Trend Micro's PC-cillin Internet Security.

Editor's Note: For reviews of five top software firewalls, see Safety First: Five Firewalls For Your Desktop PC.

	10 Free Ways To Keep Your PC Safe
	1.  Get Free Anti-Virus and Anti-Spyware Protection   2.  Check Your Security Online   3.  Get Free Wireless Network Protection Software  4.  Use A Free Firewall  5.  Encrypt Your Data  6.  Protect Yourself Against Phishers  7.  Disable File Sharing  8.  Surf The Web Anonymously  9.  Say No To Cookies  10.  Protect Yourself Against eBay "Nigerian Scams"

5. Encrypt Your Data
No matter how good you are at making sure no one else has access to your PC, someone might be able to get in. It could be a hacker, or someone who is on the network you use. If you're at work, it might even be a co-worker who sits down at your PC when you're out of the office.

The solution? Encrypt data that you don't want others to see. Most encryption programs cost money, and many aren't particularly easy to use. But Cryptainer LE from Cypherix is both free and simple to use. Install it, and it creates a new, encrypted volume on your PC. Create files inside that volume, or move files into the volume, and they're encrypted on the fly. You can work with them as you would any other files, without having to use a password.

When you want any files or folders hidden from prying eyes, highlight them and click the Unload button in Cryptainer LE. They'll suddenly vanish. To make them appear, click the Load button, and they're back after you type in a password. Only those with access to the password will be able see them.

Protect your data from prying eyes with the free Cryptainer LE. Click image to enlarge.

The software is also useful for those who use small USB flash drives to carry around data. You can encrypt the entire drive so that if you lose it, no one else can see the files on it.