IDX search refers to a a tightly defined, limited set of fields, that consumers can access with or without registration.
Here is one example: http://repdx.com/home-search/
VOW or virtual office sites require registration, and offer a more comprehensive set of data beyond simple IDX searches.
Here is a VOW example: http://repdx.com/daily-listings/
(registration required, per MLS rules)
Tom Inglesby, Broker
RE/MAX Equity Group
Through the MLS in Atlanta, we have the ability to set-up what is called Client Gateway. This is essentially a website for the Buyer (or Seller) to look at properties in the MLS that the Agent sets up to meet certain search criteria. It is an AWESOME tool. Once set-up, the MLS automatically sends them updates to their Gateway like new listed property, property status updates, etc. They don't get every single detail found in the MLS; however, it gives them most everthing they need to see. I would speak to a local Agent and ask if their MLS has something like this. Good luck!