I shot in JPEG. I am not really familiar with RAW at this point as I am still a fairly new DSLR owner. Its something I would like to learn more about though.
You're likely not familiar with JPEG either.
Your T2i makes 14-bit Raw images, but only 8-bit JPEG images.
Ironically, the T2i makes every image a Raw capture, at first. To then convert it to a JPEG, the camera throws away, forever, 80% of the color data it originally captured, so it can get down to that 8-bit limit.
14-bit means there are 16,384 tonal gradations per color channel in a Raw. 8-bit means there are only 256 tonal gradations per color channel on a JPEG. There are 3 color channels red, green, and blue (RGB).
JPEG files are smaller. Generally, the Large/Fine quality JPEG file size is 1/4 the file size of a Raw capture. But as mentioned, compressing the file size that mich, and particularly losing 80% of the image color data make editing JPEGs a touchy proposition.
As bad as that is, it gets worse. JPEG converts the image into 64 pixel squares called MCU's or Minimum Coded Units. That means no more pixel editing.
Why should I use Raw?
http://en.wikipedia.org/wiki/JPG