If you are using a Windows machine or even a Mac running Windows in a virtual environment, you need to pay attention to security. At the very least, you should always have at least one program for each of the major security threats: antispyware, antivirus, and a software firewall (if you don't already have a router-based firewall). Some antivirus suites have begun to include antispyware in their software, so if you have antivirus software, check to make sure you're covered. But if you're reading this and you don't have software to cover these three areas, we strongly suggest you visit our Download Security Center and browse through each of the categories.
To get you started, we've rounded up the top free antispyware software options. Most of these programs offer a paid upgrade with added useful features, but we made sure to only pick software that followed through and removed spyware without the need to buy during the initial trial. It's important to note that each of these programs has its own set of algorithms and different times they update their definitions, so we recommend using two antispyware programs to make sure you catch everything.
Spybot Search & Destroy was one of the first antispyware options available and it still is a fairly strong contender for finding threats. Other useful tools, including Secure Shredder, complement the program's basic functionality for completely destroying files. The interface is pretty dated, but with all the added extras of this 100% free program, it's worth a look.
Ad-Aware Anniversary Edition has been in the antispyware game for a long time as well. They have always been close to the top of our list for antispyware detection, but you'll need to pay for added features like scheduling and shield-based protection. With several interface refinements, faster scanning times than previous versions, and numerous other enhancements, this might be the easiest-to-use Ad-Aware yet.
Spyware Terminator is a free option that offers an easy-to-understand interface and lets you schedule your scans for the time most convenient for you. The real-time protection for this program is stronger than most, but can get distracting as you'll need to personally approve many actions. Fortunately, you can designate a lower level of protection to keep you safe without all the hand-holding. This is one of our favorites at Download.com for its relatively quick scan times, free real-time protection, and the ability to designate how deep of a scan you want to use.
CounterSpy makes it simple to schedule and customize spyware scans or run scans on demand, while also offering an adjustable level of real-time protection. Added features like a PC Explorer to browse running ActiveX controls and running processes are useful additions. This one offers a 15-day trial with which you'll be able to remove threats found by CounterSpy, but you'll need to pay to use this program regularly.
SuperAntiSpyware Free Edition, despite its rather uninventive name, is a solid antispyware program. This program offers a number of options for the types of files you want scanned. Like many of the programs listed here, you'll need to pay for the full version of SuperAntiSpyware to unlock the ability to schedule your scans and use real-time protection.
Malwarebytes is our Editors' Choice at Download.com so we recommend it as one of your choices in your antispyware arsenal. Scans are quicker than other programs in this category, and Malwarebytes is often able to distinguish between real threats and common false positives. You'll also be able to scan individual files on demand and a handy File Assassin lets you delete locked malware files. You'll need to pay to set up regularly scheduled scans and real-time protection, but with this solid program, registering is worth your money.