this is just a thought...
there are many different ways to strength train and get definition and more muscular w/o weights if you would want to go that route...pilates, stretch band, exercise ball, some kinds of yoga, callanetics, ttapp and isometrics...

also, another alternative might be a Leslie Sansone tape where she uses either real light weights, belt or bands. That way you get cardio and strength work at the same time.

I tend to get "bulky" so I have tried and enjoyed these and gotten some real good results. And its nice to have variety.