Plug 'n Play or a better name for it is Plug 'n Pray does not always work. When using any computer for Linux, you have to research the hardware to know what chip that it uses. The following is a list of PCMCIA/CardBus and ExpressCard devices that are said that should work.
http://tuxmobil.org/pcmcia_linux.html
http://tuxmobil.org/expresscard_linux.html
There are hardware compatible list for other sites, so I suggest looking through those too.
Any hardware like a WiFi card will need some manual setup. If the WiFi card is not supported natively, ndiswrapper should get the device partially working.
I have an internal WiFi in my notebook computer. It is an Intel WiFi model 3945. It works after doing some manual configuring to connect to a network. It takes a few minutes to have the hardware settle down and be ready to scan for WiFi networks.
It is easier to connect to non-encrypted WiFi networks.