We're using the Linksys Wireless-B WPC11 wireless card in our laptop, with a Linksys router.
I can only attest to the merits of that: and that Linksys' customer service is the best I've ever had. They have helped me with repeated problems multiple times.
I finally figured out my 2.4 Ghz cordless phone was interfering with my wireless network, so upgraded that instead to a 5.8 Ghz phone. Is it possible this might be causing your problems as well?
Yeah, it's possible -- but I fiddled around with using different wireless channels.
That and the range expander seem to have solved my problem.