I worked in Uganda earlier this year and had a similar problem. Check out E-med, they have a good report on diving and anti malarials.
http://www.e-med.co.uk
Look under diving medicals.
What I was told was that diving while on Larium is a total no no.
Others, as long as you dont have any side effects should be ok. Obviously if you choice of tablet makes you drowsey then diving will not be a safe option.
Malarone was the drug of choice for us. Its very expensive, about £40/week ( but if the boss is paying!), no one on my crew had any problems with it. Also you only need to take it for 2 days before and seven days after you travel, so you could be clear before you need to go diving again.
Do check that it is effectice against the strain of malaria prevelant in the region you are visiting.
Just to let everyone know, I am not a doctor or medically trained, just a diver that has to travel to unpleasent parts of the world and doesnt want to miss out on a dive.
Cheers
Darren