Vmware workstation: failed to open (The file is too large).

I just bought an external usb hard drive (Seagate 160GB Dancer) to put my vmdk files on it.
As it was already formated, i didn't check it out...damned!
After copying 46GB of vmdk, i wanted to give it a try..:
Vmware is giving me a nice : failed to open (The file is too large).

After searching on the web for this message without success, i watched the log:
failed to open (32776): Underlying file system does not support that big files.

Damned, i am on FAT32 even on a 146GB drive..
How to waste hours in copying!