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Upgrading to a draft-n wireless router? Don't toss out your old network quite yet. For some time to come, you'll probably be stuck with a few legacy 802.11b or g clients, especially devices such as Wi-Fi-enabled game consoles, cell phones, and music players. But running a mixed network of 802.11b/g and n clients can seriously degrade performance--especially when it comes to streaming video, making VoIP calls, and performing the other high-bandwidth tasks that you bought the new router for.

Instead of cramming every device onto the same Wi-Fi network, maintain your old router for use with b/g devices, and put your shiny new draft-n notebook in the fast lane by restricting access to your draft-n router to 802.11n clients only. This setup also lets you use stronger encryption on the draft-n network than legacy clients may be capable of, and reduces the number of clients sharing Wi-Fi bandwidth on either network.

But running two networks in the same location requires you to set things up carefully to avoid interference and routing problems.

First, switch your old router to access-point mode, so that it does not perform NAT routing (see your router's manual or check the vendor's Web site for instructions). Next, plug the old router into the new one via ethernet, preferably using a long cable so you can place the two routers at opposite ends of the room. (Your new router will be connected to your broadband modem and will perform routing for both wireless networks.)

Next, choose channels for your two networks that are as far apart as possible: Set the draft-n channel as high as your router will allow, and the b/g channel at the bottom, or vice versa. Configure the draft-n router to allow only 802.11n devices to connect, and set the encryption level for each network at the highest level your devices will support. For example, you might use 128-bit WPA on the b/g network, and WPA2 on the draft-n network. Finally, make sure that you have different SSIDs for the two access points so you don't accidentally log onto the b/g network with your draft-n notebook.