What is a warranty deed and in buying property that has such a deed what does the buyer have to do to protect them self and have it legal

With a warranty deed the seller is transferring ownership to the property and is also promising that they have good, clear title.

The best way for the buyer to be protected is to have a title search performed before the transfer is completed and purchase a policy of title insurance.

A great site that explains the different types of deeds is Information About Deeds (http://www.lectlaw.com/files/lat08.htm)