Question for you - are you not planning on using a realtor? Sometimes just getting in touch with a realtor and letting them know what you are interested in you can have a search pulled.
If you don't want to use a realtor -
www.realtor.com is a good nationwide site, but you won't see all the information a realtor does. There is also a secure login site called the Home Buyer Scouting report - but for this you usually have to contact a Countrywide Loan Officer and they will probably try to hook you up with a realtor. Or you can always go with a local company real estate office's website - like
www.johnlscott.com - I have heard pretty good feedback for the site.
I am a realtor - and I won't try to push my services on ya