I like Jillian Michaels 30 day shred DVD too for when I have little time and want a quick strength trng/cardio work-out. I recommend her "Banish Fat, Boost Metabolism DVD". I find it more challenging than the 30 day shred. It is a longer work-out and is more cardio/calisthenics than the 30 day shred.
It is 50min (incl warm-up and cool-down), but it is done in 7 circuits, so you can end it at an earlier, logical point if you have to. I often get interrupted by my 10-month old when I work-out at home so I like that I can stop early when I have to with this DVD yet still feel like I got a good work-out because it is fairly intense.