sudo iwlist eth1 scan
Does this produce scan results? It should. If you find your network there, pick up the ESSID.
Second: If the AP only uses weak WEP encryption, (WPA would be a lot better), you can test the connection easily with iwconfig. Like this:
sudo iwconfig eth1 essid "network_essid_here" key s:ascii_password_here
If you instead use hex password (not ascii), use 'key hex_password_here' instead of 'key s:ascii_password_here' (leave s: off).
That should get you connected - the only point you can type wrong there is the password (use s: if it's in ASCII like it usually is, and don't use it if you have a hex password; if you want to make sure, use quotes around the password too). If it succeeded,
should give you an IP within a moment, and then you should be online. If the iwconfig command tells you there is no such interface, try running 'ifconfig eth1 up' first to bring the interface up.
If you use WPA encryption instead, like you should, you need to setup wpa_supplicant OR use NetworkManager (the graphical thing). NetworkManager is easier - just point, click and type password - but wpa_supplicant isn't that difficult either.
If iwlist eth1 scan brings scan results, driver and hardware are working fine. If it doesn't, check the driver. If scanning works but connecting doesn't, it's very probably a problem in the encryption key; WEP encryption should be supported by all wireless hardware (WEP too nowadays, though) and Linux wifi drivers, so that ought not be a problem. Of course you can try without encryption first if you like; turn off all encryption from the access point (note: this is both foolish and dangerous, so don't leave it like that for long!), then just run
sudo iwconfig eth1 essid "network_essid_here"
sudo dhcpcd eth1
and see if it works. If not, there is something seriously wrong with your configuration or driver. If it works, turn on encryption and try to connect with the right key (iwconfig for WEP keys or no encryption, wpa_supplicant for WPA encryption, or NetworkManager in either case).