One of the things most professionals recommending looking for in end to end IP video surveillance systems, whether it be the camera or recording/viewing system, is universality. Basically you don't want to be stuck in a proprietary end to end system where only Brand A's cameras work with Brand A's recording or viewing system.
Some of the specifications to look for in this area are generally considered universal, such as RTSP and HTTP streaming. The security industry has been promoting as it's own, open source method of connection called ONVIF. (www.ONVIF.org) Even I have recommended on some of these threads one of the things to look for is ONVIF in the product.
While ONVIF is still a developing standard and not a guarantee of interoperability, it's supposed to be a start and a way of insuring a customer's freedom of choice. Some false...