GeSWall

Product: GeSWall 2.6
Company: GentleSecurity 
Website: www.gentlesecurity.com
Type: Free
Requirements: Windows 2000/XP

With GeSWall, you can safely surf the Web, open e-mail attachments, chat, exchange files regardless of the security threats posed by the Internet. GeSWall protects you from intrusions and malicious software by isolating vulnerable applications.

Isolation applies an access restriction policy that effectively prevents all kinds of attacks, known and unknown.