Ad-Aware 2007 scans your computer for known data-mining, aggressive advertising, scumware, keyloggers, trojans, dialers, malware, browser hijackers, and tracking components. Ad-Aware 2007 tools can detect hazardous content on your computer, clearly identify their threat level, and then give you the ability to remove unwanted content (Lavasoft).These free software easily download in here.
These free software system, requirements
RAM: Operating system + minimum 50 MB (100 MB recommended)
Hard Disk: 50 MB free space recommended
Windows XP (Home, Pro)
Windows Server 2003
Windows 2000 (Pro and Server)
Web Browser: Internet Explorer (version 5.5 or higher), Firefox (version 1.5 or higher), or Opera (version 9 or higher)