I have a Toshiba Satellite 2430 S-255 and I am pretty happy with the
Fedora Core 2 install. I recently purchased the Netgear 802.11 g
wireless card WG511T. In Linux, it recognises the card because when I do
a "dmesg" it gives all of the card parameters correctly. Also the Wi-Fi
monitor detects the device and the Atheros chipset on which this card is
based. Unfortunately I do not know how to get this card activated, i.e.
how to make it recognise that there is a wireless router at home.

Use the wireless-tools package. There is a program named iwconfig that
allows you to specify many settings (e.g the ESSID).

Thanks a lot for all the help. I finally got my card to work and this is how,

The card is a Netgear WG511T and is a 802.11G card. The first thing is
that this card is based on the Atheros chipset. Luckily there is a Madwifi
project on Sourceforge which makes drivers available for this chipset. I
obtained the related drivers out of cvs:

cvs -z3 -d:pserver:anonymous@cvs.sourceforge.net:/cvsroot/madwifi \
co madwifi

This will create a madwifi directory and you need to do a ./configure, make
and make install. This should compile the drivers ath_pci, ath_hal and
wlan. Besides this the kernel source and a libdaemon version (> = 0.5) are
also needed. In addition, installing the wireless-tools package helps a
lot.

Next I did a modprobe ath_hal, modprobe ath_pci, and modprobe wlan. At
this point I am not sure if this is required or not but it worked.
An iwconfig should then show the card specific parameters.
Then in the /etc/sysconfig/network-scripts an ifcfg-ath0 file is required.
The one that I have is a blend from various sources so I am just pasting
it here,

STARTMODE=hotplug
DEVICE=ath0
BOOTPROTO=dhcp
WIRELESS=yes
HWADDR="your mac address"
ONBOOT=yes
MODE=Managed
ESSID=any
KEY="your wep key"
MII_NOT_SUPPORTED=yes
USERCTL=no
PEERDNS=no
TYPE=Unknown
IPV6INIT=no

After this do a ifup ath0 this should set it working. Also, I have noticed
that both the ethernet and wireless do not coexist together so you might
want to do a ifdown eth0 before bringing the wireless device up.