We used Linda Sears of Morris Realty as a buyer's agent, and were very pleased. We signed a written agreement with her to be our buyer's agent. Otherwise, she would just have been a transaction agent with no obligation to represent our interests.
As our buyer's agent, she was legally obligated to represent our interests. She represented us quite well!
A good source of info:
http://homebuying.about.com/od/buyin...907-buyagt.htm
Google "buying agent vs transaction agent" for many more good sources of info on the subject.
I wish you all the best, and hope you find your dream house! Happy hunting.