Connection keeps dropping

I just bought a Linksys WRT54G router and a Linksys wireless PC network card
for my laptop. Everything works fine for my other computers that are wired
to the router. My problem is my connection keeps dropping on my
laptop(wireless). One minute I'm surfing a page, the next minute, nothing
works. It
still tells me on my taskbar that my signal is good but no small flashing
green monitors!! They just go dead. Can anyone tell my why? I tried changing
the channels, comes back, but it still drops again.
Help!!!