Lenovo T400/T500 hard drive module work's fine after removing locating lug on the back of the module.
The cheap one I bought [manufactured in the philippines] from ebay,had sloppy manufacturing tolerances when it came to the plastic surrounding the sata connector,making it impossible to push the module in,but was easily fixed with a sharp knife.
The module has no locking device on it,but is tight enough on it's sata connector,that it seem's it wouldn't fall out without dropping the notebook
Pity that the matrix storage manager has no option to configure raid0.........another oversight by dell
How's your M4400 going ofelas?
if you are looking for a hard drive caddy specifically for the M4400 to add a 2nd hard drive