Checking the list of devices at http://www.linux-wlan.org/docs/wlan_adapters.html.gz,
I see that the Dell True Mobile 1150 uses the orinoco driver.
What do you mean that the card is "showing up in Mandrake"? What tool are you using to see it showing up? How do you get it to "show up"?
Have you installed the drivers from http://linux-wlan.org/?
Have you adjusted the configuration files in /etc/pcmcia? Specifically, /etc/pcmcia/wireless.opts and /etc/pcmcia/network.opts? Not too hard really, the files themselves contain a lot of instruction on what should be entered.