I just successfully rooted my X10a, which is running firmware 1.6. I did not install the 2.1 update through Sony, because I have an AT&T phone, and so am not yet eligible for the update. I am wondering, what is the best way to upgrade to firmware 2.1? Do I have to debrand my phone to do so? Or do I have to install a custom ROM? A lot of forums seem to direct people here, but I don't really understand what this tutorial does.