The driest place on Earth is the Atacama Desert in Chile. It is a coastal desert by the Pacific. It is dry because of the cold water of the Humboldt Current, which creates a cool inversion. Also, the Andes Mountains to the east, blocks moisture from the Amazon. Some places in the Atacama Desert see no rain for centuries!

The Atacama Desert is not really that hot and it is actually quite pleasant and mild.
Antarctica is interesting one. It holds the world's freshwater in ice caps. Yet, it is also one of the driest places in the world. One area, Dry Valleys, has not seen rain for 2 million years! Yes, 2 million years!

Also, it is very cold. The reason it is so dry is because of the katabatic winds, which pulls down cold and dense air, which sucks the air dry at the same time.
http://en.wikipedia.org/wiki/Atacama_Desert
http://www.universetoday.com/guide-to-s ... -on-earth/
http://en.wikipedia.org/wiki/McMurdo_Dry_Valleys