Go to free.avg.com and download the basic version.
Start the downloaded file.
Decline the optional elements: "security tool bar" and the proposed change of the home page as it's not needed.
It starts automaticaly. Let it update it's viral database and do the first scan.
It will now start automaticaly with Windows.
Electro
April 2011
Download Grisoft AVG for free,and follow instructions.
Rich
October 2010
I can answer this question...
How can instoll Anti-Virus softwear in my computer?