If your PC is infected with malware, it runs at less than its peak. So if you have a sluggish system that seems to go on the fritz regularly, an infection may be the cause. Use these programs to kill infections and stop them from attacking your machine in the first place.
Comodo Firewall Pro
This excellent free firewall has been rated as one of the top firewalls by the independent testing site Matousec, which found that it has the highest level of "anti-leak" protection (in essence, a measurement of a firewall's effectiveness). It offers two-way protection, and a great view into your system and your Internet connection as well.
Download Comodo Firewall Pro | Price: Free
A lightweight freebie, Avast won't weigh down your system by consuming too many resources or RAM--yet it does a great job of killing viruses and live-scanning for them. It also scans e-mail (including Web-based e-mail) for viruses, and offers protection against instant-messaging viruses, peer-to-peer dangers, and other threats.
Download Avast | Price: Free
AVG Anti-Virus Free Edition
AVG's excellent free antivirus software is similarly prudent with your system resources and RAM. It's simple to use and easily configurable, and it protects your machine. What else could you want?
Download AVG Anti-Virus Free Edition | Price: Free
Keep your system in top running form by stopping the installation of ActiveX-based malware and other types of spyware. A particularly useful feature is the System Snapshot, which will take a snapshot of your PC so that if it gets infected, you can revert to a clean version.
Download SpywareBlaster | Price: Free
Spybot Search & Destroy
A longtime favorite free program, Spybot offers live protection from spyware installation, and scans your system for preexisting spyware and kills it. The software has a restore function, as well.
Download Spybot Search & Destroy | Price: Free
Using more than one antispyware scanner is a good idea. So even if you have another, this free one, which has been around for years, is worth trying. It does a great job of scanning, and it lets you put potentially damaging software in a quarantine area, where you can later restore the item if it isn't dangerous.
Download Ad-Aware 2008 | Price: Free
Trend Micro HijackThis
If you think your PC is infected with spyware, but your spyware killer can't track it down, try this freebie. After HijackThis analyzes your Registry and file settings, it creates a log file, which you can upload to a HijackThis Web forum for the community to analyze. Unless you're an expert, you should not try to use this tool to fix problems.
Download Trend Micro HijackThis | Price: Free