WEP Key(s) Confusion

I am running XP Home. I have a Linksys router and am
trying to set up WEP. I had it working for my three
desktops using 64 bit encryption. Using a passphase the
roter generated four (4) lines or keys of 10 digits each.
I copied those onto each computer and it worked. I now
bought a laptop and the XP software/wireless setup only
requires one key line that you must retype...but I have
four generated lines from the router. I tried entering
just the first 10-digit line and although the laptop shows
great signal strength I cannot cannot. With WEP disabled
everything works fine. Can you help?