Well good points noted starting from the bottom
being no security and then grow. Helps on
trouble shooting as well.
So you have followed the guide where is it that
you start to have a problem.
Please post the output of ifconfig or at least
note wether there is another interface besides eth0 or Lo.
There is are a couple things to check one being that you are
on the right channel (caught me once or twice) and that the
ssid is correct. Check them to see if the settings are correct.
The best guide is at ndswrapper:http://ndiswrapper.sourceforge.net/joomla/index.php?/component/option,com_openwiki/Itemid,33/
since the author is there for more hints.
If you are using dhcp and you have the other settings correct
try as root:
dhcpcd wlan0 <-- being the interface name