'Drivers' are applications that control the interaction between certain hardware you might have and the rest of your hardware and/or the OS.
IE a 'graphics driver' controls the way programs run on your PC (including your OS) send visual data to your graphics card and the way the graphics card processes that data to be sent to your monitor for display.
Aside from using windows update to update your OS, the only real 'drivers' that need regular updating are:
- graphics card drivers: you can download these from the manufacturer's site (nvidia/ati usuall)
- soundcard drivers: you usually only have to install these when you first set up your system, they dont usually need updating nor do a lot of updates get released.
- directx: I don't think windows update updates your directx so I tend to check once a month or something for newer versions
These are the most common, and basically if you just run windows update and check for graphic card driver updates once a month or so you should be fine.