Hi David.. I've actually had the previous problem in the past! When connecting to my WEP secured wireless network at home, I've had no problems. It was connecting to my university's open network that gave me problems! Probably because my university required visiting a authentication webpage soon after..
To connect to my home network, I would type the following commands:
iwconfig eth0 essid "My Wireless Network"
iwconfig eth0 key my-hex-key
ifdown eth0
ifup eth0
And then it would kick on. :/ Give it a try?

----- Original Message -----
From: David Latka <d_latka@yahoo.com>
Date: Saturday, June 6, 2009 10:14 pm
Subject: [Gumstix-users]  Overo Fire/Air help configuring WEP networking
To: gumstix-users@lists.sourceforge.net

>
> Okay, I don't give up easy...but I give up.
>
> I can connect to an unsecured wireless network, but I can't get
> connected to
> my WEP network.  If you have WEP working, could you please
> share your your
> working interfaces file with an example of some correct WEP settings.
>
> Thanks in advance,
> Dave
> --
> View this message in context: http://www.nabble.com/Overo-Fire-
> Air-help-configuring-WEP-networking-tp23907267p23907267.html
> Sent from the Gumstix mailing list archive at Nabble.com.
>
>
> -----------------------------------------------------------------
> -------------
> OpenSolaris 2009.06 is a cutting edge operating system for
> enterprises
> looking to deploy the next generation of Solaris that includes
> the latest
> innovations from Sun and the OpenSource community. Download a
> copy and
> enjoy capabilities such as Networking, Storage and
> Virtualization.
> Go to: http://p.sf.net/sfu/opensolaris-get
> _______________________________________________
> gumstix-users mailing list
> gumstix-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/gumstix-users