The Internet is littered with spyware, tiny apps that live on your hard drive and either direct you to advertising sites you don't want or record your Internet surfing activities to download even more advertising. We look at five antispyware products and recommend the best.

If spam is your personal nightmare, consider the havoc adware or spyware may wreak. These tiny applications either feed advertising to software already running on your computer or, worse, collect data about your Internet surfing habits, then broadcast that data to marketers worldwide. Often, you don't even realise that you've installed these apps because they either piggyback on free software that serves another purpose (say, the ad-serving app Cydoor, which is included with the Kazaa file-sharing program) or, often, download and install via nefarious Web sites (notice a new default home page or search engine for your Internet Explorer?). The end result is that your browser may default to unusual search-engine sites or produce odd search results, and you may see exponential growth in the number of pop-up ads that litter your desktop while you surf. How can you find out whether your machine is infected? We look at five antispyware apps that will scan your PC and remove these pests.

Our favourite spyware killer
Once again, Spybot Search and Destroy is our Editors' Choice. It's free -- even the periodic file updates -- and it offers both basic and advanced modes and includes the widest variety of customisation. In our informal tests, Spybot was also the most thorough of the five antispyware products we reviewed. If you're new to the spyware threat, it can't hurt to download a free (no strings attached) copy of Spybot to see whether your system is infected.

Equally good options
The other apps we reviewed are all equally good; they'll do the job -- but they required payment or annual subscriptions, didn't catch everything, or weren't as customisable as Spybot. Running a close second is Ad-aware 6.0 Standard Edition. Ad-aware has been around for years and isn't about to concede ground to the new kids on the block. It continuously updates its look and functionality, and paid versions of Ad-aware offer proactive spyware-blocking and network capabilities. Another familiar name is PestPatrol 4.2, which is also not free but offers a soothing interface and a powerful scanning engine. New to the scene, McAfee AntiSpyware is currently available only as a download from McAfee Security or as a feature within McAfee Internet Security. Like the paid editions of Ad-aware, McAfee's AntiSpyware and Webroot's Spy Sweeper both offer automatic spyware blocking to prevent new spyware from ever taking root on your PC.

Whether the app is free or paid, any of these antispyware applications should remove the most dangerous spyware from your PC.

Spybot Search and Destroy

Spybot Search and Destroy is adaptable for both beginning and power users, and it's a great way to keep your home PC free of spyware. Best of all -- it's free.

Ad-aware Standard Edition 6.0

If you're a penny-pincher, the free version is a good choice for spyware protection.

PestPatrol 4.2

PestPatrol offers fast and thorough spyware protection, but it is also the most expensive antispyware app we reviewed.

McAfee AntiSpyware

McAfee AntiSpyware's automated spyware scanning makes this a sensible addition to any PC's security measures.

Spy Sweeper

A well-designed program, Spy Sweeper is both classy and effective.