I think by now there are a lot that are Vista compatable.
I use Norton Internet security 2007 and have no problems with it.
I read a lot of people don't like it because it is a resource hog. In my case I don't find that to be true.
Go to a computer store and ask what their techs. use for Vista and what works the best with the least amount of trouble.
Which is the best security suite that is compatible with vista?