I’ve just begun to research WPA + PCI wireless card in Ubuntu.

Follow installation instructions for ndiswrapper:
http://ndiswrapper.sourceforge.net/mediawiki/index.php/Installation

Using a ZyXEL card:
http://ndiswrapper.sourceforge.net/mediawiki/index.php/List#Z

Tools to use:

• iwconfig – to configure wireless network interface.
• iwlist wlan0 scan – scan for access points using wlan0 interface

WPA with ndiswrapper:
http://ndiswrapper.sourceforge.net/mediawiki/index.php/WPA