i agree with ddviper that this will be a life style change. I used to be 265 and now i'm 215. Listen to ddviper, and also, don't do cardio and weights on the same day. alternate between them. To best get results from cardio, you have to "switch it up". Say Tuesdays you do a timed run where you run as fast as you can for 1 mile, eventually you'd want to build up to 3 miles. Thursdays you'd want to do interval, where you so a jog for 30 second, run for 1 min 30 sec and sprint for 1 min, then run for 1 min 30 sec and jog for 30 sec, and so on, until roughly 30 mins is up. Then say on saturday you can try and do a slow pace run, 6-7 miles? Just build up to that point.
I'm sure you know about weights and breaking down your muscle group so i won't get into that.
oh and if its weight you're trying to loose, when you do weights make sure you're sweating and that you keep your heart rate up. Don't rest for more than 30 seconds (this will cause you to do lighter weights though). 1 min is usually recommended, but to keep your heart rate up and to keep you sweating do 30 seconds. Also push yourself!.