I have been running Eset Antivirus 4.0 for approximately 9 months and have had great success with it. It runs quietly in the background and does not cause my computer to run slow like my previous antivirus did. I have Windows 7. I don't know if that makes a difference. I feel bad for the reviewers who had so much trouble with the product. I have not had any virus problems since using Eset NOD32. It updates automatically, but I do run my scans manually. So far I am very pleased with the product.