But by making a few judicious changes using the security tools within Windows Vista -- and in some cases by adding a few pieces of free software -- you can lock down your operating system like a pro.

1. Use Windows Security Center as a starting point

For a quick overview of your security settings, the Windows Security Center is where you'll find the status of your system firewall, auto update, malware protection and other security settings. Click Start, Control Panel, Security Center, or you can simply click the shield icon in the task tray. If you see any red or yellow, you are not fully protected.

For example, if you have not yet installed an antivirus product on your machine, or if your current antivirus product is out of date, the malware section of the Security Center should be yellow. Windows does not offer a built-in antivirus utility, so you'll want to install your own. For free antivirus, I recommend AVG Anti-Virus 8.

2. Use Windows Defender as a diagnostic tool

The malware section of Windows Vista also protects against spyware using Windows Defender. The antispyware protection in your antivirus program usually trumps the protection Microsoft provides, but there are several good reasons to keep Windows Defender enabled. One is that every antispyware program uses a different definition of what is and is not spyware, so redundant protection can actually offer some benefit.

Another reason to keep Windows Defender enabled: diagnostics. Click Tools, and choose Software Explorer from the resulting pane. You can display lists of applications from several categories such as Currently Running Programs, Network Connected Programs and Winsock Service Providers, but Start-up Programs is perhaps the most useful. Click on any name in the left window, and full details will appear in the right pane. By highlighting, you can remove, disable or enable any of the programs listed.

3. Disable the start-up menu

Windows Vista keeps track of all the documents and programs you launch in the start-up menu. This can be convenient for some users, but it can also compromise your privacy if you share a computer within an office or household. Fortunately, Windows Vista provides an easy way to tweak this setting. To protect your privacy, follow these steps: