Someone already mentioned Nod32, by ESET.com I bought it and ditched Symantec and Norton. My computer is so much faster and I haven’t had any issues with the new programme. I use Firefox and haven’t used IE for years. This computer is using Vista and I like the accelerated speed now that the other 2 programmes are gone.
We used Panda on our LAN here for three years before switching to Nod32 last year on the recommendation of a friend who's even geekier than I am. Panda is great, but Nod32 is better and very light on system resource usage.