Similar problem here. I have ndiswrapper set up and the driver installed, but the driver I've got doesn't seem to work. checking the system log, I found :
kernel is 64-bit, but Windows driver is not 64-bit;bad magic: 010B
Tried the Vista drivers too, but that was even less productive; all I get are a slew of "unknown symbol" messages.
Is there another driver for Lenny 2.6.26-2-amd64? Or another strategy I could use?