ok, i got an mx900 mouse. got it working.

The problem started after installing logitech software.
Everything went to he.., it seems its impossible to use the bluetooth hub with dell bluetooth.

the dell bt didnt work, the machine froze with messages like "cannot load btrez.dll -nw"

i had to do some system restore, uninstall dell bluetooth and then install it again.

i got the mouse to work, but i cant use the mx900 hub with dell 8600, and not the logitech mouse software to configure the buttons.

one other problem is now with the mouse enabled, i cant transfer any images from my phone, sony ericsson t610, over to my dell again.

this was truly a painstaking time to get things right.