Running some variant of Linux is probably the safest way to browse, but in the real world we all use Windows at some point in the day.
I have liked Eset Nod32 for a while now. Its not free, but its good. Lately I have also been using ClamWin, Avira, AVG, MalwareBytes, Spybot Search and Destroy, and Adaware.
If I need to repair something already infected, the only way to go is to either put the hard drive in another uninfected computer and scan or use a boot disk like Hiren's. If you are using a boot disk, make sure to update the virus signatures.