Hi Colette!
I am in training for an October marathon, so for at least the past five months running has been my primary form of cardio. Right now we run on average for 3 or 4 days a week, with Saturdays always being our long mileage increasing run. Throughout the past 5 months crosstraining has been the only thing that has saved me from overuse injuries. For crosstraining I have used both Cathe Cardio Videos (although I usually do try to use a little lower impact, so no MIC to give the joints a break) and the Tank Top Rotation. I have also added periodic days of spinning, powerstrike, Mindy, and swimming. I feel lately that I am in the best shape of my life and feel that it is the result of all the crosstraining we are doing. I am not only able to run faster, easier, and for longer periods of time, but have also noticed that when I move to another type of cardio activity that it is not like starting over. In the beginning, we were running 5 days a week, and both of us (I run with my sister-in-law) were having the first twinges of knee pain, shin splints, and general pain. Since we started crosstraining our injuries seem to have decreased and I can always approach our runs with a higher level of enthusiasm. Sorry that this is so long, you sound like you are doing great things, especially since running is such hard work. Just wanted to share how crosstraining has worked wonders for me. Best of luck!