RAM won't be a problem...99% of the time! I wouldn't worry about that...just make sure the case is unplugged when you put it in. (Obviously!) Your computer will automatically recognize it...(hopefully!) and you will be able to check in your system props in Windows.
The same goes for the vid card. However, as far as drivers go for the vid card, it sometimes depends on what you had before, and what kind of programs you have installed with the old one. For example, if you have an ATI All-in-Wonder or something, by pulling out that card and restarting, your computer is going to want to start the 30 million programs that ATI uses with that card. However, because you have a new card, it is going to error out several times before calming down.
One thing to do would be to uninstall all of the unnecessary programs before you even take the old card out, then shutting down, installing the new one, and starting up. That will save you the hassle of clicking out of 400 error boxes. But from a technical standpoint...it can't hurt anything. (Unless you have an overclocking program that will immediately try to OC it when you boot.)
Windows will probably install all of your drivers, but I still recommend just installing the drivers from the CD, or getting them from the company's website. Make sure you go there regardless to check for updates.