I don't have an ATI card so this is a bit of a guess, but I would guess that the ati-driver package is the open source driver and you are probably using the proprietary driver. If so, you could remove the ati-driver and it would not hurt anything. If that is the only blocker, you should be all set.
You might want to search in the forums to see what people have to say about updating world. In many cases there is no particular reason to do so. Just update the packages when you need to to fix a problem, or if there is a security fix.