Since I don't have much experience installing driver manually, I think when you install a newer driver for your device, it will automatically remove the old one and install itself after that.
But, I recommend you to install ThinkVantage System Update and let it help you to get the right drivers, download and install them for you. In fact, it's really easier and help you to maintain all the drivers you need for your computer, and IMO it's the most valuable advantage of using a Thinkpad with ThinkVantage technology
