When it comes to gaming, some genres simply aren't good for use with game pads and controllers like the Xbox 360 uses from the perspective of PC gamers. Sure console gamers will argue that the gamepad on their Xbox 360 rocks for Call of Duty and some will even claim they will pwn PC gamers using a mouse and keyboard. The PC gamers out there know the score though.
That said there are some games that many PC gamers like to play that plain suck on the keyboard and mouse control system. Games like racing sims and flying games are perfect examples. If you have one of the new Xbox 360 wireless controllers and you have a hankering to play a game on your Windows 7 PC that needs a controller you can use the Xbox wireless controller on your rig.