Congratulations, you've successfully gained root access to your Android device, maybe even using CNET's how to root your Android video as a guide. Now comes the hard part: installing a customized version of Android. We've got that covered in a video, but be careful: this one's for advanced users only.
Before we begin, let's review some of the reasons you might want to install and run a custom Android ROM. It's highly likely that there are Android features your phone company or hardware manufacturer has decided won't get pushed to your device, and many custom ROMs provide those. There are also features that modders have introduced into ROMs that aren't included on stock Android builds, such as adding a reboot option to the power button instead of just turning off the phone.
You're also likely to get significantly better performance from a custom ROM, especially when you load up your own kernel. Custom ROMs often support interface modifications such as themes, too. Basically, you get more control over your phone.
Oh, and in case you didn't know this by now: rooting your phone voids your warranty. Installing a custom ROM pretty much obliterates it. There are a few methods for downgrading your phone back to stock, and though they're not simple, CNET TV has a How To do that, too.
The custom ROM used in this video is CyanogenMod, which is in use on more than 125,000 Android devices and is one of the most popular ROMs. I'm going to install it on my colleague Antuan Goodwin's old Droid 1, mostly because that's the first spare phone that showed up. ROMs can be tricky things, so be careful that you use what I tell you here as more of an introduction or loose guideline for how to install a custom ROM. Definitely look up how to install the ROM of your choosing on your specific device.
To get started, create a backup of your system. Download and run a backup app like Titanium Backup, then download the ROM Manager app from the Market--either free or paid will do. Tap the app and then choose Flash ClockworkMod Recovery. Tap Motorola Droid and then give the app root permission, if prompted.
If the app crashes, just allow it to force close and run it again. If the flash was successful, you'll see a box that reads, "Successfully flashed ClockworkMod Recovery." ClockworkMod Recovery is a customized version of the Android default Recovery screen, and it allows for more choices such as Nandroid backups.
If you've bought the premium version of ROM Manager, there's a slightly automated way to do this. Jump into the app and select Download ROM. Tap CyanogenMod, and be sure to check the Google Apps option. After the install you can Backup Existing ROM and Wipe Data and Cache. If the Superuser asks for root permissions at all during the process, be sure to check Remember and Allow. From there, your Droid will reboot into recovery, wipe your data and cache, then install Cyanogen. When the install finishes, it will reboot directly into CyanogenMod.
If you didn't buy the ROM Manager premium, you can still install a ROM relatively easily. Go to CyanogenMod.com and download the latest version. If you use Google apps like Gmail, also download the Google Apps package. Cyanogen decided to spin off the Google-sourced apps to avoid rights conflicts with Google. Then connect your phone to your computer, enable USB mode, and place both the Cyanogen and Google Apps ZIPs in the root directory of your SD card.
Next, boot into ClockworkMod Recovery by turning off the phone, and restarting it holding down the X key along with the power button. Use the D-pad to navigate. Choose Wipe Data/factory reset, then Wipe cache partition, then Install ZIP from SD card. Select Choose ZIP from SD card, then go for the CyanogenMod update DOT zip. Then install the Google Apps update DOT zip. Once the installation has finished, select GO BACK to return to the main menu, and choose Reboot Now. Your phone ought to boot into CyanogenMod.
If it fails the first time but you can still navigate, reboot it again. Of course, if it doesn't do anything at all, you've probably got yourself a pretty little brick.