Hey Helimutt!
I'm flying in Tanzania at the moment and although it is generally considered a high-risk area for Malaria it much depends on where you're going to be stationed (I suppose Everett in DAR?). If you're going to be in the Arusha / Kilimanjaro / Mount Meru area or elsewhere in the highlands don't worry at all, pretty much no Anopheles mosquitoes around in these areas as it's simply too high. If you stay in the lower inland parts, around Lake Victoria or Dar Es Salaam have some medication at hand to take it when you get sick. As one of the previous posters mentioned use Coartem instead of Malorone. You can get it here for 12.000 Shilling (~8 USD) and it works faster, better and with a fraction of the side effects of Malorone. You can get Malaria Quick Tests in every pharmacy, too (careful with false negatives though!). I would not take prophylaxis if staying longer than the average tourist, your liver will not be thankful.
The best way to go about Malaria is prevention anyway: after ~5pm use Mosquito repellent, cover unprotected skin, sleep under a fan, use a mosquito net (check for holes!) and spray your room about an hour or two before you go to bed. A good advice my AME (frequent Tanzania traveller) gave me: bring your own net, bring a bit of rope and bring a wall hook or nail. This way you can fix a mosquito net anywhere.
Have fun and if you need any help give me a shout! Oh, and good luck with TCAA
