Windows 7 beta is available for download, but you must install antivirus software to protect and secure windows 7 from viruses, worms, trojans and malware. 3 popular software companies have release Windows 7 compatible antivirus software for immediate download.
Kaspersky Lab has released a technical preview of Kaspersky Anti-Virus for Windows 7. The technical preview is a complex solution for securing computers running under Windows 7 and the prototype includes an antivirus component with a fully functional firewall and anti-spam filter. Its also includes a heuristic analyzer, which detects and blocks as yet unknown malicious programs. There is a direct software link out there.
Symantec has released Norton 360 Version 3.0 Beta, which claims to be compatible with Windows 7. It is free to try out after you fill a form with your country name, email and accept the terms of usage; a product key reaches your email inbox instantly.
AVG has released special antivirus versions for Windows 7 for both AVG Internet Security ($54.99) and AVG Anti-virus ($34.99), but both cost money. I prefer AVG free, but it still does not support Windows 7, but I hope it will soon.
If you downloaded Windows 7, download antivirus software too to keep your computer free from viruses.