HTC Incredible :: Reverting To Stock 2.1 ROM - Preventing Upgrade To 2.2

When I first bought my incredible, I was ecstatic about how well it performed and everything that it did. Aside from downloading a few apps, I had no desire to augment or root it.

When the 2.2 ROM came out, I have to admit, I was hesitant about installing it because I figured "why mess with a good thing" but my phone was insistent. Every time I unlocked it, it was telling me to upgrade, so finally I did.

I've been miserable ever since.

Apparently this new ROM made the touch screen extra sensitive. So much so that when I hold it (I am LEFT handed) it is constantly thinking I'm touching the home button and responds accordingly. This is because the way I hold it, the thumb side of my hand is near the home button and though it's not pressing it, just being near it, beside it, etc, is enough to trigger it. Even plugging in the phone to charge or link to the computer causes the home button to go crazy.

In addition to this, the camera, which I was so pleased with and took excellent pictures all the time under any circumstance, has now become sub-par. I don't care about 720dp video, I care about taking great pictures, which my Incredible used to do, but now it has problems with lighting, I'm constantly having to adjust the ISO instead of leaving it at automatic, and whereas it used to do fine with people in motion, now these shots are blurry 100% of the time.

This has led me to the conclusion that I need to somehow get my phone back to the 2.1 ROM.

Now, I've searched the forums and I've found two sets of instructions that seem to both be getting me to what I want.

One is
How to downgrade and root your DInc from 2.2 |

The other is
Unroot - The Incredible List

Considering I've never rooted my phone at any point and I'm trying to get back to the original 2.1 (unrooted) Incredible ROM that came with my phone, I was wondering which set of instructions is for me (or is there another I have not seen).

I also wanted to make sure that PB31IMG.zip is the ROM I'm looking for as both reference that same file. I want to make sure this will get me back to the original 2.1 where I want to be.

My second question is this, once I get back to 2.1, how do I keep my phone from wanting the upgrade? I do not want to go to 2.2 and if I recall, when the prompt came up, I only had the option to "Install Now" or "Install Later"... there was no "Do Not Install" option.

I would like to go back to 2.1 and STAY THERE without being pestered to upgrade every 5 minutes!

Just so you know, though I've never rooted a phone before, I'm not skittish about this process, I'm a network administrator, I've hacked windows mobile phones before and though this is Linux, I'm confident that given instructions, I can follow them correctly. In addition, I'm not the least bit concerned about the potential of losing all my data or apps or even "bricking" my phone. I know it's a risk and I'm prepared to take it.