The new Microsoft Security Essentials software is going to launch today, supporting 8 languages and being released in 19 countries (at the moment, the link still says "beta", but this will switch over in a few hours). This should provide free anti-malware cover to users and is perhaps worth considering for Windows 7.
http://www.microsoft.com/security_essentials/
Download URL:Microsoft offered a beta version of Security Essentials ... to about 75,000 users in June, but quickly stopped it when that target was reached. Two weeks ago the company thanked beta testers for their help and said that the polished edition of Microsoft Security Essentials would ship "in the coming weeks".
The software was commended by independent testing firm AV-Test GmbH after it pitted Security Essentials against nearly 3,200 common viruses, bot Trojans and worms. Security Essentials will run on Windows XP SP2 or later, Windows Vista and Windows 7
Source : PC Advisor
http://www.microsoft.com/security_essentials/