I have the Xti and I love it. Even with the "cheap" kit lens which is all I have so far. For what I use it for, I could not justify the extra expense.
How good of a photographer are you? Will you be able to shoot the difference in cameras? Or maybe buy the less expensive camera and use the money you save towards a quality lens. The price of the 30D is body only I believe.
Good luck, let us know what you choose!