Once you've set the username and password and you have access to the DD-WRT Web graphic interface, it's time to flash the upgraded, full-featured version of DD-WRT. Click the Administration tab at the top of the Web interface and on the resulting menu select the Firmware Upgrade tab. In the Firmware Upgrade menu, select Reset to default settings from the After flashing, reset to drop-down list, and then click the Browse button to find the final/upgraded firmware. Select that file, click the blue Upgrade button at the bottom of the window, and let the upgrade process run its course. This operation usually takes a few minutes to complete, at which point the router will reboot.

When the router completely reboots, access its Web graphic interface one more time (by typing 192.168.1.1 into your browser). You'll have to set your login credentials again. Then configure your wireless and security settings, along with any other ISP-related requirements, and you're finished.

If you're unhappy with the open-source firmware you've installed, you can always switch back to your router manufacturer's stock version. But we suspect that after enjoying the benefits of open-source firmware, you'll never want to go back to a stock router.