We need to know whether it is a wireless card problem or a networking problem.
Is your card detected and the driver installed but you cannot get on the network
or is your card not detected or can't find the driver? In the latter case
network manager will show no device. In the former case there will be a wireless
device but no network. If you right click on Network Manager in the system tray
does it say Enable Wireless?

Also, from a terminal type lshw and tell us what it says under network adapter.

I ran lshw and this is what I found.

Network unclaimed
Description: ethernet controller
product: AR242x 802.11abg wireless PCI express adapter
vendor: Atheros Communications
physical ID: 0
Bus info: pci@0000:02:00.0
Version 01
width 64 bits
clock 33 MHZ
capabilities: cap_list
configuration: latency=0

It does say enable wireless and I tried to enter my ssid and was unable to type
in that box.

www.ubuntugeek.com/atheros-ar5007-wireless-with-madwifi-on-ubuntu-804-har\
dy-heron.html

Do I run this command from a terminal window.

sudo apt-get install build-essential

Yes that would be correct. It will prompt you for your pass word since
you are now doing a root user command. You must have a connection to order to
install this. OK

Do I run this command from a terminal window.

sudo apt-get install build-essential

Yes. I'm sorry I haven't followed this thread to know exactly
what you wish to do, but I use my Ubuntu 8.04 (formerly 7.10
before the auto-upgrade earlier this year (which was impressive))
for all my astronomy apps (compiling a lot of programs) and here's
the full sequence from my CHANGELOG of what I found necessary to
be able to build the programs I wanted:

$ sudo apt-get update
$ sudo apt-get upgrade
$ sudo apt-get dist-upgrade
$ sudo apt-get install build-essential
$ sudo apt-get install manpages-dev
$ sudo apt-get install manpages-posix-dev
$ sudo apt-get install manpages-posix
$ sudo apt-get install libc6-dev
$ sudo apt-get install gcc-doc
$ sudo apt-get install libx11-dev
$ sudo apt-get install xorg-dev
$ sudo apt-get install x11proto-print-dev
$ sudo apt-get install libxp-dev
$ sudo apt-get install apt-file
$ sudo apt-get install devscripts fakeroot

I am new to wireless, but it sounds like your wireless is working and it is just
a matter of setting it up to work with Gnome. Left click and choose Create New
Wireless Network. If you have an open
network in your area you can choose Connect to Other Wireless Network.
If it is encrypted, then you will need to know they type of security and the
key.
If you choose Manual configuration, then you need to choose Unlock.This
will allow you to turn off roaming mode if you use only one network and
want to be connected to only one network.

I am just blundering along but mine works as I have outlined.

I tried that and that didn't seem to work either. If you have any other ideas
please let me know. Thanks for your help.

While I am an experienced Linux user I consider myself a wireless newbie. Like
many here I am feeling my way, sometimes in the dark. My wireless is on my eeePC
and is Atheros. Since getting my eeePC I have installed 8 or 10 distros with
varying results which I will share, hoping that others will learn from my
mistakes, even though they reveal my appparent ignorance.

I have successflly installed many distros but not all are equal. Only a few have
been able to get the wireless to work, Ubuntu 8.04, Mandriva One 2008, gOS based
on Ubuntu 7.10, Xandros that comes with it. A few will detect the modem, but
either the tools are inadequate or my skills lacking to get it to work. Since
Ubuntu 8.04 works so well, I have not had as much patience as I usually display
in getting it to work and give up sooner than I usually do.

My point is that if one distro doesn't work try another one. The desktop seems
to make a difference in terms of what tools you have to work with in getting it
to work. Gnome has a better Network Manager than most and it works well with all
forms of encryption. I have tried WiCD (pronounced wicked) on Geubuntu and found
that I could not get my wireless to work and noticed that it did not support WPA
only WEP which is a problem since my system is set up with WPA Personal. I found
that I could not get KDE's network manager in KDE 3 and 4 to work with the same
hardware and the same base (Ubuntu 8.04) which may be a testimony to my limited
skills more than anything.

Here is the sum total of what I have learned through trial and error. You won't
get the best detection and recognition of your wireless if you are running an
older kernel. Newer is better. This is why Mandriva 2008 works for me, but not
PCLOS which is based on Mandriva but is comparatively dated. The second thing is
that you need good tools to get your network set up once your wireless is
detected and installed. Gnome works for me. If you are running a secured network
you must set it up first in your network manager. Otherwise you will not connect
automatically. Gnome seems to set it up for roaming by default, so if you want
to be dedicated to one network you will have to change the setup.

I have not had any luck with KDE except in Mandriva One 2008, but it uses its
own tools, not the standard KDE tools. I have not got any XFCE or other desktop
to work with my wireless. This has nothing to do with the desktop itself or
detection, but the tools to run the network and make use of the wireless. My
wireless seems to be present, but the tools cannot get my wireless to work with
my network settings.

If people tell me that their wireless isn't working I do not know whether they
have a wireless problem or connection problem. If it is wireless I would advise
running a newer kernel first or even changing distros if it is chronically
outdated as a starting point. If it is a connection problem then I woud look at
what tools they have available.

Finally, I have learned to be more sympathetic with other users as wireless is
finicky compared to the simplicity of ethernet.