I have a Netgear WG511 v2 wireless PCMCIA card, and spent a couple hours getting it to work in ArchLinux.

You need to: pacman -S ndiswrapper wireless_tools pcmcia-cs
And manually download the windows driver for the wg551v2.

Or, if your version of the Linux kernel doesn't match the ndiswrapper version, you'll have to download and compile it, yourself.

ndiswrapper Source
ndiswrapper Installation instructions

I haven't used the wlan or wireless scripts in /etc/rc.d/ for one reason only: they don't work.

First, make sure your pcmcia driver is loaded properly.. I simply run the Hotplug service.
If you don't have a /etc/rc.d/hotplug script, run: pacman -S hotplug If you don't wanna use hotplug: modprobe pcmcia and possibly modprobe yenta_socket

The variables:
YOUR-IP-ADDRESS: If you want to use dhcp, follow 6b; if you want a static ip, use 6a
ROUTER-IP-ADDRESS: Your router should have static IP Address, perhaps 192.168.0.1 or 10.0.0.1, or 192.168.1.1
ESSID-NAME: This is your "network name", your router sets this, usually. Find it with step 5.
KEY-VALUE: This is the 10-digit WEP key that you set in your router.

Once you have everything:
1) Extract the wg511v2 driver
2) cd Windows\ XP
2) as root, run ndiswrapper -i WG511v2.INF
3) ndiswrapper -l should now display "wlanwg511v2 driver present, hardware present "
4a) add alias wlan0 ndiswrapper to your /etc/modprobe.conf file
4b) modprobe ndiswrapper (If your version of ndiswrapper is incompatible with your kernel, you'll get an error here.)
5) iwlist wlan0 scanning should display a bit of interesting information, including an ESSID line.

Either: 6a) ifconfig wlan0 YOUR-IP-ADDRESS
Or: 6b) dhcpcd wlan0

7) route add default gw ROUTER-IP-ADDRESS dev wlan0
8) iwconfig wlan0 essid ESSID-NAME
9) iwconfig wlan0 key restricted KEY-VALUE

You should now be connected

Sources: