Barbara:
No worries at all, its just my personal mileage. I had a hard time getting started running again, and now find that much running makes my knees and ankles ache like I have the flu. Now I race recreationally, and its quite the thrill
Jumping rope is an exremely good workout, just ask Boxers. Its a great way to supplement your workouts, search the internet for some rope workout plans.
And for your running, let me impart some training advice:
You can't just get much faster by just running/cycling/skating/skiing. Speed work begets speed. You need to find an interval training program that takes advantage of your natural ability to go faster.
IE: wind sprints. Obviously, you have to have base fitness mileage.
Firstly, don't try to increase your speed yet. You need to go a touch slower and start bumping your mileage up. Force yourself to relax and go just a touch slower and add 1/2 a mile per 5-8 runs. When you can run 3 miles without stopping even at a slow pace, then its time to start running intervals. A great place for that is on a track.
4x4x100's: You need to be able to recover between each sprint. As you get started, this might even be a walk inbetween sprints. Warmup by fast-walking or light jogging 1/2 a mile (800=2 laps). When you reach the straight away, give 'er hell for the length of the straightaway. Recover (fast walk or light jog) for 300 (the rest of the lap). Hit it again. Try and do it 4 times. Cool down for 2 laps. Do this 2 days a week. Start timing your sprints and laps.
Strides: Warning! You want to be on a level grass field for this. If at anytime you feel pain or discomfort, stop. Start at one end of a marked field. At a slow gait, jog 50, cool 150, jog 50. You're going to use a very exagerated running step. Imagine you're a gazelle, push off and stretch your back foot out far and raise your front knee high. Be very careful with this, it can cause injury. But done with patience, you're training your legs to take longer steps, which in turn will help you put the sprints to good use.
Bleachers: Find a set of stairs. Run up them, run down them. Run up, run down. A set of High school bleachers are great, just start with 1/2 the heigth, go across, come back down, across, up.
Good luck!
CRT: Have you thought about a cyclocross bike? Great for bombing around and you can run skinny road tires for higher speed stuff.