I would like to recomend this great Anti Virus Programme from Grisoft.
It is free for all single PC home users.
Unlike Norton and others it does not hog your memory and Cpu.
It is quick and simple to use with free updates and schedule scans.
It will check your emails, file transfers and will heal any infected files or quarintine them.
If you want a decent AV software without all the fuss and complications then give this a try.
Free Anti Virus