Backup your data
Buy a seperate Firewall, learn how to configure it. Ones that integrate with the router or modem are okay but less flexible.
Have an AV system that updates automatically or do it yourself religously.
Run AdAware or somesuch as a regular check-up or if you have problems like mysteryously appearing toolbars (iSearch is a bastard but the latest AdAware Pattern kills it) or opening browser windows.
Malware and spyware are the only things that have got onto a work computer or home computer of mine, ever. I've always had viruses stopped by virus scanners, or known that something with TWO file extensions is trouble.
That way you can use a product that offers about the highest level of compatibility with the websites out there it's reasonable to expect.
All other browsers I've used fail badly in displaying a website on a regular enough basis to make MSIE a good choice.
It's like saying spectacles with big plastic lenses that don't work good for all viewing distances are safter and better than varifocals made of glass. Yes, if you get punched in the face they are, but it's more pleasent to avoid being pounched in the face and waer decent specs.