I have exactly the same lan drive as you do and have exactly the same trouble. I remember having the same problems when I first installed Vista a couple fo years ago. Going to the MacPower website and downloading the most recent firmware worked that time. I tried the same thing this time, and it didn't work.
If you want to try for yourself, go to
Macpower - LAN Disk Firmware and follow the instructions to update the firmware. Make sure to click on "
Link Removed due to 404 Error" when selecting which firmware in step 2.
I might add that I have only tried it LAN mode, not USB.
If I find a solution, I'll let you know.
Good luck
UPDATE (15/01/09):
Mine now mounts in explorer as a network drive! I think it must have been an windows update that happened yesterday that fixed it. I also used a program call
LANDISK Utility v1.0.0.4 that works with the LAN drive and was able to connect to and map two network drives from it. I thought I didn't work, because they didn't appear in explorer straight after I did it, but I booted up today and voila.. there they are.
I hope you had the same success.