If your main goal is to lose weight the biggest impact you can make is how many calories you're eating. In a month I guess I'd recommend just doing some sort of pretty aggressive diet. Soulman and Busto seem to know about those. If you want to keep eating a bunch and lose weight, then do a ton of cardio and lifting I guess, but good luck it will be much harder to lose weight without eating less.
As for exercise, do you want to do something for a month, for life, ???
To just lose weight you don't have to do any sort of exercise but to look better and be stronger, lifting weights is a good idea. If you want this to be long-term definitely start in on barbell lifting. If you just want to do something easy and stay active, pick up an active hobby (basketball, tennis, running, long walks, hiking, etc.).
Oh and even though it won't directly address your goals, purchase a black foam roller and lacrosse ball to do muscle release on your muscles and soft tissue (SMR). I think you're not much younger than I am (31) or maybe not younger and I think you'll find it's really great for quality-of-life since you've spent so much time at a computer. And if you plan to lift weights or do any heavy physical activity, doing soft tissue work is just a great idea in general:
What is SMR?
SMR stands for Self-myofascial release and allows you to help your muscles be more pliable. While stretching helps the overall length of your muscle, SMR will help you with the tone of your muscle - key to preventing injuries and allowing for optimal stretching and mobility. SMR should help you remove knots from your muscles however, if you have significant injuries or muscle issues, ART may be necessary to truly rehab your muscles. ART is outside of the scope of this but it's recommended to find a specialist who has biomechanical certification in your area for best results: [link to online ART directory].
What equipment is needed for SMR?
Roller: A foam roller or PVC pipe that you can roll on to hit large muscle groups and break up soft tissue adhesions.
Rollers come in many different densities (white = less dense, black = most dense). And you can always "graduate" to a PVC pipe (wrap in athletic tape for grip) or rumble roller (dense foam roller with knobs) once you're not getting as much out of your less dense rollers.
Ball: A small ball of some sort that you can lay or lean on to apply pressure to large and small muscle groups to break up soft tissue adhesions.
A lacrosse ball is generally ideal however, beginners can use a tennis ball if there are too many surface adhesions to work with the harder lacrosse ball. Also note that any small round object would work and some people may prefer a baseball or even softball.
Stick: TheStick can be really useful for hitting areas like the hamstrings or calves that are difficult to hit with a roller when trying to balance on the muscle group and relax into the pain of the adhesion.
I tried rolling once and it was painful – how hard should I go?
When you start rolling, it can be quite painful if you try using a dense roller or lacrosse ball so take your time working up – you’ll likely want to start with a white foam roller. However, SMR work should be painful! It is a sign that you’ve found a tight area with adhesions that should be broken up. Get used to relaxing your muscle into the pain for the best results. Also, try to stay relaxed in general – if you’re gritting your teeth and tensing your face, chances are your muscle isn’t as relaxed as it could be. Don’t be afraid to take it slowly with a painful spot and not put as much pressure/weight on the roller or ball as you being to loosen it up.
Is there a written primer for SMR from an expert?
Sure, Eric Cressey and Mike Robertson have a nice primer on T-Nation you can read to get started:
http://www.t-nation.com/free_online_...44261362.hydra. This should be good for beginners but to really zero in on problem areas and unlock your muscles optimally, you'll want to start using more advanced techniques.