Glad to see another T2i user. Got mine for Christmas this year
If you're new to non-automatic mode shooting, I just read through "Understanding Exposure" by Bryan Peterson, 3rd ed. It costs about $22, and includes some full-page and half-page photos explaining the content that the book has to offer. I found it very helpful, and would recommend it to you.
I second the use of Lightroom 3. As a college student, I got mine on discount for $80.
So far, I've used it for white balance and exposure corrections. It's unbelievably powerful and includes a "publish" feature that sets up a webpage of sorts if you want to display your shots on your personal website. Mine, here, was made using Word for the main page and LR for the individual catalog sites: www.users.wpi.edu/~stevec
Overall, it's a very powerful piece of software.