A site like
www.hardgainers.com can give you some tips.
I'm an ecto/endo (a nice mix, huh?) so find gaining muscle a constant effort. Even when I get really strong, there is not much visible muscle unless I flex.
I found that P90X worked really well for my upper body. What worked well was lifting as heavy as I could, with the recovery periods and exercise sequencing that allowed for the muscle to regain more strength before hitting it again (vs. straight-set workouts), the recovery week, which allowed for more recovery (recovery is especially important for we ectos/hardgainers).
You can in corporate some of these concepts with Cathe's workouts. Choose a three-day split workout (like the GS series), do each workout once a week (maybe doing another lower body workout if you need to), like upper body workout 1 on day 1, lower body on day 3, and upper body workout 2 on day 5 (space out the upper body workouts to allow for more recovery of the muscles, especially the shoulder).
Pause the DVD between sets as needed for more recovery, and/or between exercises. You might even want to up the weights and limit your reps to 8-10. Make sure the last 2-3 reps are tough, and that you couldn't do another rep with good form, at least with the last exercise of a group.
To help with fat burning, incorporate an interval workout 1-2 times a week (in P90X, Plyo X kind of serves this purpose. For Cathe, it's the Imaxes), as these are the most efficient types of cardio workouts as far as calorie burn is concerned.
After 3-4 weeks, do more of a recovery week: focus on functional fitness/core and stretching.
It's hard to both gain muscle and lose fat at the same time, so you might want to focus a bit more on one first. For someone who is not really overweight or looking to lose a lot, I'd go with the muscle gain first, using the above protocol. Especially with your weight, I'd have to guess that you really don't have a lot of muscle.
Be sure to follow your weight workouts with a 'recovery' type fueling, which contains a ratio of about 4 parts carbs to 1 part protein (the carbs provide the glycogen that helps the body get back into 'build/repair' mode instead of staying in 'breakdown' mode (started by the weight), then, within an hour or so, have a meal with a higher level of protein (don't go overboard on the protein, though, 20% is a healthy maximum: too much protein has quite negative effects, including increased homocysteine levels that can lead to cardiovascular problems).
When you want to focus more on fat burning, using circuit-type weight workouts, which have somewhat of a cardio effect, and 'sculpt' more than build, like Jari Love's workouts, for example (the best example of this kind of workout that comes to mind).
I don't know exactly what you are doing right now as far as working out and eating, but whatever you are doing, it's not working (and one definition of insanity is doing the same thing while expecting different results!).
Another thing you might try is a rotation with Cathe's CTX series (taking longer pauses between weight sets as necessary, and heavying up). Though I'm a bit hesitant to recommend it because of the repeated impact (5 out of 6 workouts have plyo moves) and the excessive (IMO) number of workouts that contain step (4 out of the 6), which can make it hard on the knees and lower back (I cut a planned 3-4 week CTX rotation down to 2 1/2 weeks because my 'tell-tale knee' was telling me it had had enough, even with my modifying some workouts (though not enough, apparently--I guess I got too caught up in the thrill of the workout when I was doing it!) to lower impact.