This is absolutely doable, as long as it is not an Indian holiday when traffic can be extra bad. I suggest checking with the cab company if they think traffic will be bad. I posted recommendation for a driver under "Driver in New Delhi" post.

You will also have time to stop by Fatehpur Sikri, a UNESCO World Heritage Site, on the way to or from Agra.

In Jaipur there are beautiful palaces to visit. Amazing jewelry and textile shops. On the road exotic desert country with camels etc.