finally!
i found a nice hard drive that works with the USB port in the M3
Its the Samsung S1
it uses a 1.8" hard drive running at 5400rpm (like the ipod drives)
it's 120GB ( i think they also have a 160GB version)
i bought the 120GB for $90 from Microcenter
it's also available on amazon
http://www.amazon.com/Samsung-HXSU01...4866413&sr=8-1
it fits in the ipod holder in the arm rest and you use just connect it with the mini-usb cable it comes with
it also comes with a 8" cable along with the short one pictured
i put my whole collection of 4535 songs and after it was done indexing it works great
just takes about 1-2 min to start playing when you start the car