This is exactly what I was looking for. I wanted a decent controller for my computer which would be durable (unlike my old one) and had 2 analogue sticks and 2 analogue triggers (very useful for driving games like need for speed). The only other one I found with 2 analogue triggers was one by Logitech but it was much more expensive.
Being actually designed for use with a console by the first party producer of the console you know it cannot be a bad product and, as it's Microsoft, you know it will work without any problems with your PC. If on Vista you do not even need to download the drivers, just connect the controller to a USB port and it will auto-install itself.
I prefer the wired version because:
1) it's cheaper
2) I don't have to keep on buying batteries
3) I use it with my laptop so I play close to it anyway. In fact, the cable is pretty long so you won't have a problem unless you have a massive TV and need to sit quite a few metres away from it.
For £18 I doubt you can find a better controller.