Get a yoga DVD and do it as often as possible! I tried cycling and running to slim my legs down and they actually ended up bigger as I had bigger muscles which were still under a layer of fat
Stopped doing the running and cycling, started yoga, and because it lengthens the muscles they slim right down. Worked wonders for me, and my legs now fit into skinny jeans! Before if they went on my legs they were massive on my hips
I've been doing C25K - I've just got to week 9 (running for 30mins). I've lost 4 inches on each of my thighs. Admittedly they are still pretty huge, but much more in proportion to my hips and waist now.