SMC 802.11b PCMCIA WIRELESS

living in the country I am forced to use a satellite D/L and ISDN upload for
my broadband internet, thus giving me a modem and a receiver (2 usb's). My
setup is, one older laptop as the Gateway, 2 newer Dells as the working
computers. The gateway doesn't get used at all but to connect to the
internet while the other 2 computers are for surfing (windows internet
sharing) What my problem is, the internet will go completely dead on one or
both of the 2 computers (but never the gateway). The network is still strong
as I can file share. Sometimes I can be looking at sites like EBay with lots
of pages and it will stop working but other sites might still work. My
equipment:- SMC 802.11b PCMCIA 11mb x3. [IP address' set. 192.168.0.X
with 1 being the gateway.] [no encryption, no passphrase]
I am using SMC wireless card manager as I am not that clued up on this
stuff.