I worked for an ISP for a while. You almost always won't get as good a connection through wireless as you do on ethernet. Although most of the time it is a channel issue causing the problem. Even if there's only 4 networks in your area. If the laptops got Windows Vista or Windows 7, go to the program list, right click on command prompt, select run as administrator. Then type the following quoted command without the quotation marks
"netsh wlan show networks mode=bssid" hit enter that'll tell you every network in range even if the ssid's hidden and even if the signal's low. Most ISP send their routers out on channels 1,6 and 11 You may or may not find this when you check. But try a channel that has no-one on it and no-one with at either side of it if possible. I.e channel 3, if no-ones on 2 or 4. If the router's N-draft, check the laptop is capable of N-draft. If it's new it probably is. Other unlikely but possible causes are "some" cordless phones and Wireless tv senders.
If none of that helps it's likely the physical obsticles in your house, like walls e.t.c In which case you could try buying a home plug kit, that will send the internet connection through your electrical system as long as it's all on the same circuit.
http://www.amazon.co.uk/Twin-85Mbps-.../dp/B000SO94FA
As always, do your own research. Hope this helps