It would be helpful to know if this is the first time that you have used
Ubuntu. If so, then you may not know much about Ubuntu and its wireless
history. If you have used it before then you know that it is setup
differently from Windows. Wireless is both hard and easy to set up.
It is easy if it works the first time because you have a well supported
wireless card. It just works which without any drivers which is what many
people encounter. Atheros wireless seems to work best for many. If you have
a less well supported card such as Broadcom then it is not so easy. However,
if you have a Windows driver disk then any wireless card can be made to work
via ndiswrapper. This is the last resort, but it usually works.
So it would be good to know what wireless make you have. Also it would be
helpful if you opened a terminal in Ubuntu and typed lshw. Scroll back to
the networking section and post what it says. If it says UNCLAIMED then it
means that your card is detected but there is no driver installed. In which
case you go to System, Administration, Hardware drivers and see if there is
one in the repositories for your card.
If not, then we go the ndiswrapper route. This involves adding two packages
from the repositories in Synaptic called ndiswrapper-common and ndisgtk.
After installation run ndisgtk and it will prompt you for your Windows
driver disk.
You cannot download it if your wireless is not working so you have two
options. One is to search for it on the Ubuntu CD. It is there. And the
other is to attach an ethernet cable until you have it installed through
Synaptic. You need to re-boot to make it available because it loads as a mod
when you boot.