Firstly, you need to find some of this.
It's called DIESEL INJECTOR LEAK OFF PIPE and can be found online, halfords or if you just want to buy it in the correct length your local motor factors will cut it and sell it per foot. We sell it for £1 per foot so anything around this is reasonable.
Wind your window all the way down and you will see a rather large gap.
All you have to do is cut it to length (IIRC about 1M per door) and drop it into the groove between door and seal, (DO NOT PUT IT INSIDE THE SEAL WHERE THE WINDOW COMES UP) like this.
When it's finished it should look something like this, the window should go up and down without any problems and you won't have any rattles. (Flick the window to check this)
Now, it's not guaranteed to stop EVERY rattle but I would say 90% are gone. Only the really harsh bumps seem to make it rattle now.
Glad I could share. :thumbup:
Any questions, ask away.
This is a video of how easily removed it is!