antivirus

Nod32 isn't free, so I resorted to Avast, which has a free version. Avast can really slow a computer to a crawl, though.

AVG has poor detection rates.

AVG is terrible. It allowed me to get a very nasty virus, and I installed Avast just to clean the computer, but I had to format and reinstall Windows, because a complete wipe was the only way to surely clean the system, and the virus had already compromised WinXP. Now, I use Avast, but it really likes to slow my computer down (to a crawl), so I don't really recommend it. AVG is okay. It just doesn't detect everything. Avast has much better detection rates, but it slows down your computer way too much. Also, the best anti-virus is virus prevention, so that means checking all files whenever they're loaded, including images and text files. Avast does all this for you. It checks email, webpages, images, text files, dll and library files, executables, anything and everything. It even prevents a known virus from even running at all, so, whenever it detects something, everything locks up, and Avast asks you what you want to do. Even if you're careful what you do on the web, you can easily get infected without even doing anything, and a simple task, like looking at a photo gallery, can compromise your security in Windows. In the Linux world, you don't have that problem, so I switched to Ubuntu.