Multitouch, custom ROMs, maybe even Sense UI on your Nexus One? We’ll it all begins with rooting it first. So thanks to Paul at Modaco here’s how.

I. Root the Nexus One

1. Download Superboot (first download link on the page)

Superboot

2. Once it is saved to your computer, unzip it to your C: by right clicking it and clicking Extract Files…
Once it is extracted to the C:, rename the folder to Superboot (this will make life easier later).

3. Turn off your Nexus One and then plug it in to your computer via USB cable.

4. Turn the phone back on by holding down the trackball and hitting power (keep holding it down until the fastboot screen comes up).

5. Open the Command Prompt on your computer by opening the Start Menu, then either typing cmd and hitting enter in the search box (for Vista and higher) or by clicking Run and typing cmd and hitting enter (for XP).

6. Once it opens type the following with hitting enter at the end of each line:

cd\
cd C:\Superboot
fastboot-windows devices

*Your phones serial number should display proving that it is connected and your computer can see it.

Then type:

fastboot-windows oem unlock

7. Then follow what the screen says to do on your phone and select Yes.

*You may get an error in the command prompt, just ignore it.
**Also your phone may reboot, if it does just turn it off, then turn it back on by holding down Power and the Trackball to get back to fastboot before continuing on to the next step.

8. Now, while the phone is still connected, go on your computer to the Superboot folder and open it. Inside you will see a file called, install-superboot-windows.bat

9. Double click install-superboot-windows.bat and wait for it to finish. All done, rooted!

II. Load a Custom ROM (OPTIONAL)

theunclocker.com