The Internet is a dangerous place full of scammers, privacy invaders, and hackers intent on turning your PC into a junk-message-purveying bot. And sometimes it seems as though your options for protecting yourself are pretty sparse.

But in reality, there are plenty of things you can do to keep yourself safe. Firewalls, antispyware, and other types of safety and privacy software will go a long way toward ensuring that you never get victimized. Try these four downloads--two pieces of freeware and two shareware programs--and keep the nasties at bay.

Jetico Personal Firewall for Windows

One of the best ways to protect your PC from spyware, Trojan horses, and other software that might otherwise transform it into a spam-spewing zombie is to install a firewall that can block dangerous inbound and outbound connections. The Windows XP firewall does just half the job, blocking inbound connections only. This means that if a piece of malware gets on your PC, you're unprotected when it attempts to phone home to a hacker or to send out spam without your knowledge.

The free Jetico Personal Firewall for Windows solves this problem by blocking dangerous outbound connections. The firewall notifies you every time a program tries to make an outbound connection, so you can decide whether to let it proceed. Permit familiar and safe programs to pass through, but don't let dangerous ones make the connection. (If you're not sure what to do, search Google for the name of the program that's trying to make the outbound connection, and you'll quickly find out whether it's safe or not.)

If you're sure the software is safe, choose Handle as Application Trusted Zone when allowing it through; thereafter, the firewall won't ask your permission each time the approved program seeks to make an outbound connection. If instead you select Allow this Activity, you'll be asked for approval every time the program attempts to make an outbound connection.

The firewall also includes a traffic monitor and a log that keeps track of all network events.

AbsoluteShield Internet Eraser Pro

When you browse the Web, you collect plenty of souvenirs. Your history list identifies the sites you've visited, and your cache contains files downloaded from those sites, including HTML files and graphics. Internet Explorer keeps a list of all the URLs you type, too, along with a list of the words you type into search engines if you use the AutoComplete feature. And plenty of other software on your PC can track your Internet activity as well.

AbsoluteShield Internet Eraser Pro is for anyone who doesn't want that private information available to others. It deletes just about every trace of your surfing activity--and it does so for multiple browsers, enabling you to clean up Firefox and Internet Explorer from the same interface.

This utility does does far more than simply clean up your browser, also cleaning up Windows itself by clearing the Recent Document List, the network cache, the Temp folder, and other locations. It even clears lists of files used in programs such as Windows Media Player and WinZip.

Internet Eraser Pro doesn't merely delete the traces; it "shreds" them in such a way that reconstructing them would be extremely difficult. You can use AbsoluteShield Internet Eraser Pro for free for 15 days; to use it after that, you have to pay $35.

A-squared Free

No single utility can detect and kill all spyware. You need multiple antispyware programs to detect and kill the pests.

That's where A-squared Free comes in. It looks for spyware, adware, Trojan horses, worms, bot malware, dialers, and other ne'er-do-wells. When it finds suspect apps, it will excise them at once (if you wish) or quarantine them so you can confirm that they are malware before deleting them.

A-squared Free digs deep. Besides finding and killing spyware, it can detect "traces" such as Registry entries, and remove them as well.

On the other hand, A-squared doesn't offer real-time spyware protection and won't protect your PC against getting infected in the first place; for those jobs you need other antispyware. But A-square is free and makes an ideal second or third spyware killer on your PC.

McAfee Site Advisor

These days, it's tough to separate benign Web sites from malicious ones. Is the financial Web site you visit the genuine article, or was it set up by a scammer? How about a Web site that promises not to bombard you with e-mail if you register--is it telling you the truth? Are a site's downloads free of spyware and adware?

For a simple way to answer these types of questions about a site, try the free McAfee Site Advisor. It adds a button to Internet Explorer or Firefox; click it when you reach a Web site, and you'll see McAfee's report on the site, including the number of e-mail messages the site sends per week after you register, whether the site delivers pop-up windows, and whether the downloads on the site include spyware and adware.

McAfee Site Advisor also assesses whether a site is legitimate or a phishing lure. Advisor integrates into major search engines, too, so when you do a search on, say, Google, the search engine's results will indicate whether the site appears to be safe or not.

Preston Gralla, author of Windows Vista in a Nutshell, is filling in for Laura Blackwell, who is on maternity leave.