Avast Mac Security (formerly Avast Free Antivirus for Mac) offers three shields, on-demand scanning and WebRep clients which are automatically (optionally) installed to Safari, Chrome and Firefox browsers.
What's new in this version:
- WebShield + MailShield: Enhanced compatibility with various mail/web server configurations
- 30-day Security report
- Many fixes and minor improvements
This is not for 10.5.8 but for 10.6.8.