Michael is correct however still a valid question on home sites like Trulia. That is because they are not directly linked to the MLS and therefore rely on mass downloads on some appointed schedule. When my son used this site looking for his first home, 1 out of every 3 he sent me was already under contract. The reason he liked Trulia however was because it does have a very dynamic search tool.
I would invite you to check out the home search tool on the front page of my website at http://www.RaleighHomeSite.com
. It's very similar to Trulia but is linked directly to the MLS so should only give you active listings, plus when you create a saved search, it will automatically send you the listings very shortly after they are input by the listing agent.
If there is anything I can do to assist you personally, please don't hesitate to contact me directly!!