Quoted from Cnet
When you are using a Windows system, you need to pay attention to security which includes three major threats: antispyware, antivirus, and software 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. Most of antispyware offer a paid upgrade with added useful features. The following software could remove spyware without the need to buy during the initial trial. If you want to get a better result, we commend you to install at least two of them scan your computer.
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 quite 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. 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 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.