The ideal post-workout snack is an 8oz glass of chocolate milk.
How large are these shakes?
A healthy protein/carb combo snack is recommended after any workout, but it is very likely that the shake exceeds your requirements.
In terms of helping to repair muscle to improve strength building it is only required after heavy strength training, not after cardio at all (although still a healthy protein/carb snack like choc milk after cardio!)
Deb, in New Zealand