Firefox or chrome are (to me) the best choices. Though I like firefox's persona system better than google's skin system, AND firefox has add-ons. I am unaware of any add-ons being made for google chrome. HOWEVER, due to google chrome's lack of add-ons, and simple method of applying skins' it is a lot simpler.
I use firefox because it can be simple and complicated, complicated being that you have the ability to add things onto (like add blocker plus, or personas, chatzilla, etc.
I don't know if either one is faster than the other though, and I really doubt your firefox has a virus. You could still reinstall it.
Though in your situation, I would probably be inclined to start a-new with chrome.