I've had good luck with an old Linksys WPC-11v3 on my J720 -- works well with the PRISMNDS driver -- Ministumbler works -- no problem connecting to various APs
(although I couldn't get WEP to work on an AP at a friend's office
).
Rokland.com has them for $14.99 + shipping
(they're in New Jersey, USA
) -- I bought two of them -- UPS ground shipping is $7.41 to Ohio.
These are the 16 bit version that will work with the PCCard slot on Jornadas.
Here's the link for anyone who's interested.
RLW