I'm at a loss here, unless there is a hardware problem. Did the laptop come with windows, and if it did, did wifi work under windows? Is there a diagnostic program you can run, I've never used a Toshiba laptop and don't know what disks come with it. Maybe someone else here can chime in with some ideas.
Edit: I'll see if I can google up some answers.
Edit: sorry, it does seem like the rtl8187b has been problematic in the past, one link I found from older ubuntu forums:
I still think that it still should show up when executing lspci, but, I'm still looking.
another link with not so good news:
Unlike my Dell, it seems that this card is on the usb bus....Can you paste the output of lsusb ? Sorry, but reading some links pointed me in a different direction.