Grats on the purchase! Hope you get as much joy from the step up to DSLR as I have had :) Now you look forward to plenty of torment of lusting after lenses ;) I've not used the 75-300, I have a 70-200 F4 L which is an awesome lens. Maybe thats not long enough for what you require though. I'm currently lusting over the 100-400 L (a grand of glass :o ) - just look at the stuff Danob has posted using it, and join me in dribbling over the keyboard ;)