You consider jumping rope hardcore? Really?
Anyways, here's what I recommend. You need to alternate between aerobic exercises. Here's an example schedule.
Monday: Jog two miles.
Tuesday: Use the bike machine or just ride a bike for a couple of miles.
Wednesday: Jump rope.
Thursday: Speed walk.. and it wouldn't hurt to actually have some 2 or 3 pound weights to curl while you power walked.. you'd curl them naturally while you did your arm strides.
Friday: Swim some laps.
No matter what, you need to do continuous aerobics and watch your diet.
I don't chase, I replace.