Rajasthan appears to be relatively low risk for malaria in February, so should I take malaria meds while I'm there (for two weeks) or just try to avoid getting bitten? Obviously I'll use Deet and take all the usual precautions to avoid mosquito bites, and I have a supply of Malarone if needed, but I can't seem to find any reliable information as to the risks so that I can make an informed decision as to whether to take the Malarone or not. If it makes any difference I'm taking my 14 year old son with me and I need to decide for him too.
As you said, it is
low risk meaning that you don't really need prophylaxis.
Relatively means in comparison with other parts of India, where the prevalence isn't that high anyway.
A lot of my colleagues traveled to medical conferences and other symposia in Delhi and Rajasthan and none of them used any anti-malarials and none of them got sick.
I don't mean to be ignorant, but malaria is pretty treatable now so if something does go wrong, you can always make your trip shorter and seek medical help if you notice any of the symptoms (don't be overprotective and hypochondriac, though).
Malarone will be of no use once you get there since you have to start taking it a few days before your trip. It's also expensive and you have to take it each and every day. There is a dosage for children but since I'm not an expert in that filed, you should ask a tropical diseases professional about that.
Depending on how long you are intending to stay in India, I believe you shouldn't take any drugs if your trip is shorter than a month. There really is no need. And if it is longer, then start taking medication before the trip and buy the rest of the pills once you get to your destination. Read my answer on that subject here.
You and your son will be exposed to the same conditions so if one of you is taking meds, the other should as well.
Reid also posted some links as a comment so read those questions/answers as well.
February is a winter month in Northern India, and that produces conditions inconducive for mosquitoes to breed (stagnant water). Besides, Rajasthan is one of the drier regions of India and with it's a particularly low risk area.
I lived in Jaipur this past summer for a few months and into the beginning of the Monsoon season, saw one mosquito (not exaggerating), after the rains started. I was taking malaria pills and had brought deet but stopped using both after a week.