You may be able to use the orinoco/hermes driver set, but
I have had very good luck with the hostap drivers
http://hostap.epitest.fi/
IIRC, debian has a broken version of the driver in
lib/modules/3rdparty or some such. You may need to
delete those and compile the current version of hostap driver.
You can tell what modules were loaded by typing "lsmod"
on a command line. But I'm not a debian user so I'm not sure
of the specifics of automatically loading things
(an alias in modules.conf or somesuch)
An alternative to hostap is the linux-wlan-ng driver at:
www.linux-wlan.org
hth,
-bbeers