I run a few VPS installs and try to minimize costs as well as processor/memory utilization. I have run some tests on some antiviruses lately, deliberately installing viruses to test efficiency. I have both Linux and Windows VPS systems located on multiple hosts. Using Windows to host many of my marketing applications this is the VPS type I was most concerned with. All I can say is my results were quite surprising. I found that Microsofts own MSE (Microsoft Security Essentials) not only had the lowest footprint but snagged each virus/malware i tested it with vs. the others (Eset, Norton, Panda, Viper, AVG). Not only that, but the software is 100% free!! Antivirus: Microsoft Security Essentials Price: FREE Download: http://www.microsoft.com/download/en/details.aspx?id=5201 If anyone has anymore experience with their VPS installs please let me know as this is what I came up with my tests but I am definitely open to some other results.