my workout consists of:
20mins eliptical cardio
4 sets of 25 crunches
3 sets of 15 leg lifts
3 sets of 10 (50lb) hamstring leg curl machine
3 sets of 10 (75lb) leg extension machine
3 sets of 10 (80lb) inner thigh adductor machine
3 sets of 10 (80lb) outer thigh abductor machine
2 sets of 15 hyperextensions
instead of doing your cardio first you could either A: do all your lifting then do your cardio, many studies have shown this to increase fat loss because you use most or all of your glycogen stores lifting, leaving only fat for energy when you do the cardio or
B: change to a circuit style training for instance
4 sets of 25 crunches
3-5 min of high intensity cardio (i.e. fast run on treadmill)
3 sets of 20 hamstring leg curl machine
3-5 min of HI cardio
3 sets of 20 leg extension machine
3-5 min HI cardio
3 sets of 20 inner adductor machine
3-5 min HI cardio
3 sets of 20 outer abductor machine
3-5 min of HI cardio
3 sets of 15 leg lifts
2 sets of 15 hyperextensions
10 min of moderate intensity cardio
In option B you would go for higher repetitions with slightly lower weights because that is were you will reach fat burning potential. At 10 reps you are more in a strength building range. Throwing the cardio in between sets keeps things going, adds intensity to the workout, and keeps your heart rate up during your weight sets. You would end doing 25-35 minutes of cardio total, but it would not be as mind numbing as 20 min all at once.
My wife just started this kind of work out added to her weight watchers diet and has shedded 13 pounds over the last 5 weeks and a noticable difference of tone in her butt.