maybe try the following if you have not done so
On the wireless laptop, run network wizard, click my network place, click set up a small office/home network, make correct slection which is to select "access internet via a gateway"
again on your wireless laptop, click connection icon and do some set up such as get IP address automatically
Now, you may need to access router's set up program, set up mac address filtering etc (I think you have already done this if two computers can see/access each other).
important bit: find NAT (network address translation) and set it as NATP, also turn on DHCP server
by the way, it is a good idea to disable/uninstall firewall software when you set up network, when everything working and you put them back again