eat a regular small meal post cardio, unless it's really late in the evening, then try muscle milk.
I dont' worry about carb/protein dosage too much in post, I just eat a small meal of the good stuff (turkey, whole oats ). It's working good for me.
I do an hour or more of bicycling on work days, and 3 to 5 hours of cycling on off days, if that helps. I'm not a work out junkie but an avid fan of cycling, so I do mostly cardio, therefore I hope my comment helps.
Pre-cardio, I'll have a very small glass of protein mix (muscle milk or something else ) because it settles in my stomach easy, and I'll have something very very small to eat. Example: one or two slices of thin turkey, or half an egg, or something along those lines. I stress small, I don't want to feel it in my belly at all. And I drink a lot of water, but not enough to bloat me. That makes me feel pretty good during the cardio session.
Keep in mind, you don't really need the shakes or mixes to do this.