My Dad being on the old android verison 1.5 which is pretty ancient, since the latest one is 2.2. It was hard at first, took me around 2 hours to figure out how to do it on his phone. But it ended up being pretty awesome, since it was custom and came with the Droid X motoblur.
And a custom Rom is like a custom Windows installation, it removes stuff that the creator found unneccasery or lagging on the phone. But his phone is even faster now, and this process wasn't even really new to me as I have done it to my Samsung Captivate, which has Android 2.2.
