I know you'll get a lot of great responses to this question, but I used to struggle with less than desirable legs and I'll tell you what really helped me was 1) Legs & Glutes--which comes a DVD with Kick, Punch, and Crunch which is an AWESOME kickboxing workout that does a lot for you legs as well. There are numerous premixes on this DVD that lets you BLAST your legs. 2) You'll probably also really like Leaner Legs and Gym Style Legs, either one is killer, but Leaner Legs has a higher difficulty rating on this site. However, Gym Style Legs has these slow motion lunges which will never be easy!
3) If you don't tend to bulk in the legs when you lift heavy weights go for Slow and Heavy Legs, the heavier weights and the slower rep speed allows for control, perfect form, and real concentration on each rep.
4) Running and interval workouts (any of the IMAX workouts). Both will help to blast fat, lower your overall BF percentage and running helps to lean the legs nicely in my experience.
5) Clean eating, clean eating, clean eating
You can do all of the above and won't see the results you want, or the results you are really capable of achieving if you don't clean up the diet--which is always my sticking point;-)
Hope this helps! If you want more information about what has worked for others and different training styles just run a quick search for similar topics on this forum (this has been a popular topic-- and you'll get plenty of material to get you started):7 FYI: The search option is near the top of the screen
Mattea