Quote Originally Posted by Johnny Rasmussen
I´m also using the XTi or 400D. I have an 580EX II flash. I have loaded a canon firmware hack to the cf-card and now have access to ISO 3200. Native ISO. I also got access to more advanced focus patterns and spot metering. It works great. You will find more info here: http://chdk.wikia.com/wiki/400D if you are interested. It loads from the cf-card so it does not mess up the internal firmware.

Wow, I just loaded the chdk firmware and it's fantastic! I love the more precise ISO increments as well as the handy focus patterns. Really brings new life to that camera. I knew they were working on implementing different things on the 40D, but I never thought to check on a chdk firmware for my XTi. Thanks for bringing it to my attention!