It may be possible to replace the wifi chip in your system. However HP, Dell,
Toshiba, and Lenovo/IBM, and apparently possibly Apple, and possibly Sony,
now that I think about it, use digital restrictions to prevent the use of
third party wifi cards. This is to increase sales of after warranty parts and
service.
If it's not one of these there is probably a mini pci/pcie/half height pcie
wifi card which will work as a replacement. ThinkPenguin (I'm the CEO &
Founder) has cards for every type of slot and can find them here:
http://libre.thinkpenguin.com/
* Also there is 25% of the profits donated to the Trisquel project if you use
the above URL to place an order.