• Hide Your Network SSID
  Your wireless router tells the world that it's wide open and available to all comers. It does this by broadcasting what's called its SSID (service set identifier). Your wireless router's default SSID, essentially its name, is the same for the thousands or millions of routers the manufacturer makes. (For example, Linksys routers have the SSID of--surprise--Linksys.) So, a would-be intruder can search for networks with a few common default SSIDs from the major manufacturers, and quickly find wireless networks.
  Changing your default SSID will help, but only partially. That's because XP, as well as most war-driving software, including NetStumbler, automatically searches out nearby SSIDs, displays their name, and lets you easily connect to them. So you want to not only change the name of the SSID, but also tell your router not to broadcast its real name. That way, it will be invisible. But because you know its name, you'll be able to tell your own PCs to connect to it.
  

The steps you take to change the SSID's name and to tell your network to stop broadcasting its SSID vary from router to router. The following steps show you how to do it using a Linksys router, although it may vary from model to model:

1. Log in to the setup screen by opening your browser and going to http://192.168.1.1. When the login screen appears, leave the username blank, type admin in the password section, and press Enter. (If you already changed the password, use your new password instead.)
   Click on the Wireless tab. In the Wireless Network Name (SSID) box, type a new name for your network. For the most security, type a random collection of letters and numbers, and don't give it a name that can be easily guessed, such as "My Network."
   In the Wireless SSID Broadcast section, select Disabled.
   
2. While you're at the Wireless screen, you can do something else to help keep your network invisible to outsiders. You should regularly change the wireless channel your router uses to transmit. That way, if someone has previously tapped into your network, he won't know which channel you're currently using to broadcast.
3. Choose a new wireless channel from the Wireless Channel drop-down list.
   
4. Click on Save Settings to save all your settings.

You now have to go to each of the PCs connected to your network, and tell them to connect to the router using the new network name.

In Windows XP SP2, click on the small wireless icon in the Notification Area, and click on the View Wireless Networks button. Click on "Change advanced settings" in the left-hand column and then click on the Wireless Networks tab. Click on the Add button in the "Preferred network" section, type your new network name, click on OK, and then click on OK again. You'll now be connected to your network.

If you're running an earlier version of Windows XP, click on the small wireless network icon in the Notification Area and select the Wireless Networks tab. Click on the Add button, type the network name, click on OK, and then click on OK again. You'll now be connected to your network.
Now only someone who knows the name will be able to connect to your network.

Use Encryption:
You should use encryption on your network. That way, even if an intruder manages to somehow discover your SSID, he won't be able to snoop on the information you're sending out over the airways.

The two most common types of encryption are WEP and WPA. The WEP protocol is older and less secure than WPA, but you might be forced to use it if you have older hardware that doesn't support WPA. Keep in mind that all of your hardware has to support the same encryption standard. For example, if your newer router uses WPA, your wireless network adapters must also support it. If not, you'll have to use WEP.
The truth is, though, that for home networks, WEP is most likely plenty strong enough. You really only need to protect yourself against passersby, not against someone dedicated to break into your network. Again, though, if your hardware supports WPA, it is a better bet. And it's certainly more suitable for small-business networks.

To set up encryption, it's a two-step process.

1. First, you tell your router to turn on encryption and choose an encryption key. How you do this varies from router to router. On some Linksys models, log in to the administrator screen, select Wireless -> Wireless Security, and you'll come to the encryption setup screen.
2. After you turn on encryption, you tell each PC to use encryption. On each PC, you'll first click on the wireless connection icon in the Notification Area. Then click on the Properties button and click on the Wireless Networks tab. Highlight your network, click on the Properties button, and click on the Association tab. From there, you configure the PC for encryption.

There are even stronger methods of encryption, such as RADIUS encryption, but these often require dedicated servers or other hardware. However, if you want stronger protection than WPA can provide for your home or small-business network, there's a very affordable way to do it, without buying hardware. A new service from WiTopia called SecureMyWiFi provides RADIUS encryption for up to five network users for $29 per year. You can add more users for nominal fees; for example, you can have up to 20 users for $15 extra. After you subscribe, you'll receive instructions on how to use it, but setup is quite similar to that of WEP and WPA encryption. Note, though, that you can only use the service if all your hardware supports WPA.

Free Firewalls:
http://zonelabs.com/ - where to download one of the best free firewalls.
http://www.windowsupdate.com/ Make sure your windows security is up
to date and obtain the Windows XP Service Pack 2 firewall. (use either the XP Sp2 firewall or Zone Alarm - not both)