Locating available wi fi hotspots

I have an Inspiron 8500 and use wireless networking with WEP incryption. I
know there are wi fi spots in my vicinity because our Toshiba laptop wirless
card shows 3 of them. But I can't see them on my Dell laptop.

Is encryption filtering them out or is there some setting, checkbox or other
something I've either screwed up or forgot to check/uncheck? I assume it's
not the card or my wireless card wouldn't work with my router.

Thx . .
--
Jimbo