I doubt that it does not get deteted. It may not have a driver installed,
but it just as well could. The fact that your wireless is not working does
not mean that it is not detected. With Linux you need to set up a wireless
network connection with security password, etc. before your wireless card
will work.

Open a terminal and type: lshw

Scroll back and look for the section: *-network

If it lists your card then it is detected. If it says UNCLAIMED then you
need a driver. If it lists the card and it does not say UNCLAIMED then you
likely have a working network card.

Worst case scenario: you will need to use your Windows driver, but you
should be able to get it to work.

is it a built in or a plug in wireless card? I'm thinking since you
specified Broadcom, it's a plugin. Though someone here may have the answer
for you, You might solve it quickest by finding the model number on the
wireless card, and running a google search for "Ubuntu Broadcom
wireless" and see what sort of hits you get from the ubuntu forums. Its a
good chance there is a post with several options on those forums or this
list.

Have your drivers for your wifi ready on a CD or stored in your HD, know where
the one(s) ending in .inf are and run ndiswrapper or ndisgtk.

Often this is sorted now by using an ethernet connection to the router
and getting the current updates. Broadcom are gradually coming into
the Linux world and chances are the wireless card will be sorted