A lot of this advice tells you to go out and basically create a radical lifestyle change all at once. That generally doesn't happen. Changing things like diet, exercise, spending habits, social habits, etc., tends to work best if you slowly make small changes.
Lots of people find that diet / exercise tracking software can help them meet goals. I have a few friends using MyFoodDiary.com, and I like it pretty well. It does a nice job of giving you warm fuzzies for doing the right thing (fiber, produce, low cholesterol, etc.).
Exercise is really really important. It tends to improve mood and focus. It improves your cholesterol profile. Current thinking is that being fit is more important to overall health than being at the proper weight. So your goal is to get more exercise into your daily life. From what I understand, you can do this in 6 minutes every few days; you can walk 10,000 paces (about 5 miles per day), or do something in between.
Personally (I'm in IT too) I find it really hard to regularly go to the gym, and I hate the rigid schedule of having to go to the gym for 1 hour 4x per week or whatever. I like the suggestions of you doing small bursts of exercise while you're at work. In addition to strength / resistance training, how about:
Any of these would increase your overall activity level -- and then maybe you just have to do one strenuous exercise session on the weekend or something, like a vigorous bike ride plus weight training, or a 1x per week cycle to work.
Oh, you could also work with a trainer who could figure out a workout for you to do while at your desk.
Say "twenty-three-skiddoo" to logout.