I used to use spybot,avg,& a few others. I always wondered why my computer kept getting infected. Spybot used to be so good, avg was quite decent but took so long to scan. Then i ran Comodo firewall, SpywareTerminator,& Avira AntiVir. This combination is great for it being a freeware setup. However I have been using Kapersky internet security suite for the last 1 1/2 yrs and have tried NoD 32 from ESET security as well as their total security suite. These suites use less system resources, leave a smaller footprint, & are much much better at what they do. I haven't been infected since i started using Kapersky (unless i purposely downloaded an infected file to get the program i wanted knowing it would get thoroughly disinfected later).