Yes but thats what the antivirus is for. Most browsers refuse downloading unless you give it permission, and you can even set higher restrictions within the browser. If it gets past those defenses, than either it is a very sophisticated virus, or I allowed it to. I enjoyed firefox for a while because it had add-ons that disabled many things websites had, like adobe pop ups and scripts and many others; I am now trying IE9 beta to see how it will work out. IE is supposed to be top security, but unless IE9 drastically improves, I'm going back to firefox's flexability.
Back on topic. Really, it isn't hard. If a virus does overtake my system and I cannot get rid of it, than a simple reinstall will suffice, at least for me. I don't do work on my computer, it is only for entertainment. So I guess I am really only speaking for myself when I say I never needed pro. Someone else very well may need it, but I am in favor of keeping my system fast for games and internet only, security is nice, but too much for me is a constant pain. (Ever try buffer zone? it has to be one of the worst). Others here have purely entertainment computers as well, otherwise why would you install the best hardware out there like many of us do? If I wanted better security, I by no means would rely on Windows 7 Pro. I would buy it (Other proven security software, more than just an AV). Pro would be a nice edition, and perhaps even Ultimate if I was concerned for my system's welfare. I'm just saying I regret my decision to buy pro. I could have had a fancy dinner with the money I would have saved