I really like The Biggest Loser first work out DVD. It has 2 cardio sections that are about 20 to 25 mins long. One is 'low intesity', the other is 'high intesity'. It also has a 20 min strength and sculp, and a 20 min boot camp. I'll often do the low intensity cardio with the strength section.
I also am loving Jillian Michael's DVD's too. My cable company has like 6 different work outs from her in their On Demand section.
I also have 2 crunch Dance cardio DVD's that I do once in a while - I seriously cant dance, and so I suck at those work outs
I've been alternating with TBL DVD and the Jillian Michael's workouts for the past 3 weeks, and have noticed a big difference