Every version of windows comes with the required drivers, when you install windows xp, you will see a screen where various drivers are loaded, these are loaded for the system to work and to install the OS properly.
Similarly windows 7 also comes with a set of drivers of almost all the popular hardware till its date of release. It detects the hardware and installs all the required hardware.
But IMO install the drivers that came with your system or with your motherboard, as these drivers are generally updated versions.
When an OS is coded they add all the popular drivers of the popular hardware, like they add the nvidia drivers which will work for almost all the Nvidia gfx card, but to get the maximum out of your hardware, one must install the latest. Same is the case with the intel chipsets driver, audio driver, ati driver and so on.