If you are going to use a piece of hardware (like your wireless card) that is
dependent on non-free software you are missing the point of Trisquel. Using
Trisquel with non-free software is like polluting an environmental sanctuary.
As someone else pointed out you can get cards very cheap too that will work.
There are lots of other similar (from a look/features/feel stand point)
distributions to choose from if you would rather not. This is less damaging
to free software.
On the other hand if you want to support free software then join the club and
get yourself a real wireless card.
http://libre.thinkpenguin.com/ (25% of the profits go to Trisquel- not to
mention it helps increase the different formats/hardware available for
Trisquel and GNU/Linux in general)