After reading many XDA-Developers Forum Posts to try and figure out how to get into the Recovery Mode / Download Mode without any success, I gave T-Mobile Support a call.
After the usual noop run-down, "did you take the battery out" questions, I simply asked them how to get the Samsung Vibrant into recovery mode.
Unline the many tutorials that claim to require the Up or Down button pressed, along with the Home button then the Power, the true process is as follows:
1. Press the Up and the Down button at the same time (yes both). I too thought that button was a Toggle which only did either Up or Down, but found that in fact it does do both.
2. At the same time, press the power button.
3. As soon as the Samsung / Vibrant logo comes up on the screen, release the power button.
4. Release the Up and Down buttons.