from a practical implementation standpoint, you would be well advised to go through all the configuration and security steps with one of your laptops wired to the router and the other sitting right beside it connecting wirelessly. If something gets bollixed while you are configuring the passphrase or MAC addressing, your wireless access into the router's configuration pages will be cut off (as it should be - the keys at both ends of the connection are not matching, so no go). With one of the laptops connected by wire, you can use it to access the configuration pages and retype the key. After you have the wireless laptop running smoothly, unplug the cable to the other one and configure its wireless. That one will go much more smoothly, using all that you have learned the hard way with the first one.
Then, when the laptops are working to your satisfaction from within the same room as the router, go to the other end of your house (or where ever else you are intending to use the mobile systems) and see how the signal holds up. You already know it works up close and personal, so if it drops out now, it is a signal issue, not a configuration problem. We've heard many tales of woes about inability to configure a wifi client that is out of range of the router.