I would seriously check out Magic Lantern if you will be doing any serious video with your T2i: http://magiclantern.wikia.com/wiki/Magic_Lantern_Firmware_Wiki
From the site:
Magic Lantern is an enhancement atop of Canon's firmware that makes your 5D Mark II into the 5D Mark Free. It adds new features like onscreen audio meters and zebra stripes, as well as disables the audio AGC. It is an open (GPL) framework for developing extensions to the official software, tailored for film making needs. It does not replace the existing firmware, but instead runs along side of it. There is no need to "uninstall" it -- simply power cycle the camera to reboot to the stock Canon firmware.
This also applies to the 550D, but it has not been completely ported to that camera (I'm quite sad, as I was hoping for CHDK-like functionality).
Canon's AWB for the 550D (at least) is a bit sketchy, at least for me. Whenever I'm doing a staged shot, I have to manually tweak it so that it works and looks well. In the later firmware updates, they have said that they fixed some problems with the AWB, but since I just updated yesterday, I haven't been able to see much change.