One Care is better than nothing, but AVG and Avast are at the top of low cost scanners.
AVG 7.5 had a genuine problem with malicious websites. Some sites pop up a message that looks exactly like a message from the virus scanner, asking if you want to send a file to the virus vault.
When you click OK, you have authorized installing a Trojan horse.
Unfortunately there is no way to protect people who have administrator rights and are inclined to click OK every time they are asked. Except to block access to malicious websites, and there’s a cost involved in that approach.
OneCare is solid as a rock. I've never had any problems with it. People who object to OneCare are usually people who object to Microsoft.