A japanese coder has released Windows Drivers for the Dualshock 3 PS3 Controllers and they also support sixaxis too and even cooler is the fact they support rumble too:
There are 4 drivers in total
ds3drv_1.02 - Normal Driver
ds3drv_dx_1.02 - dx driver
SDDriverSetting - utility to tweak some settings
ForceFeedbackDriver - rumble driver, you need to install the first or second driver too
Installation:
download either the first or second driver, then open the device manager and search for the dualshock/sixaxis under hid devices, it should be called USB Human Interface Device
then choose update driver and select the driver that you just downloaded
Rumble
to install the rumble driver just right click on the .inf file and choose install
when you'll start a game you'll see a tray icon used to tweak rumble settings, the first menu option is to toggle rumble the second one will open a window where you can set the strength of the force feedback
the first value is the amplification ratio
the second one is the minimum value at which to start the small motors
the third and fourth one are the value of the large motors