450 VS shall serve you well. But since you are upgrading your PSU, you should consider about your future upgrades, and about the components you might add to it like extra drives, fans, fan controllers etc. In that case I would suggest you to invest in a more powerful PSU (VS 650, should be good) as it will take care of your power supply need for years to come.
And yes, the drivers can be installed from the card manufacturer's website or directly from nvidia's as well. Go to the download section and key in the required details to get the proper drivers for your system.