Just a quick note to throw my two cents into the ring. Effectiveness and performance as pertaining to antivirus software indeed seems to be cyclical. In the past 20 years, our IT Support business has moved to and from Norton products several times due to failure to identify and remove viral infections and/or especially performance issues (early Norton 360 products anyone?). Panda Security has become our 'go to' product for any newer computers. The 2010 version is even proving to be less of a processing hog than older versions. We have a 105 user network, running 3 shifts a day, that are all utilizing Panda as their security package except for a dozen 'older' computers that we are running Symantec Endpoint on (to reduce the performance drain). So in acknowledging that Endpoint utilizies less processing time as compared to the Panda product, we still feel better about the Panda product because in the last two years the only computers that suffered from virus intrusions were the units running the Endpoint protection. Panda's hueristics for day zero infections have proven desirable. A network admin colleague of mine swears by Kaspersky (which he has been utilizing for several years now), but has found with this latest release a real slowdown on network drive access that Kaspersky's support staff have been unable to resolve. He feels he must move away from the product for now. Again, that cyclical nature. Finally, just in case I have sounded like an advert for Panda... I only currently use their product on workstations in unmanged mode, because their server admin/protection software causes incremental loss of performance necessitating a server restart every 2 to 3 days. The lesson of the day seems to be... evaluate each and every product as an individual product and not guilty by association to previous products from the same company.