it used to be the case you had to do that when xp was the o.s. of choice but since vista you can if you want just install a new set of drivers and they will take preference over the old. they did this to allow the user to roll back to an earlier working driver if the new 1 didnt install fully.
so yeah you can just install the new without removing the old and the system should be fine with it.
but if you start getting compatibility or stability issues you will have to remove them, clean the registry and reboot.