Bear in mind that a lot of the effects you're seeing are due to filters/post-effects (e.g. the light bloom, DOF) and also shaders (normal mapping, specular, etc), so regardless of whether you have the most realistic lighting in the world, it'll still fall flat and be unrealistic if the only attention you give the models in the scene is to stick a diffuse map on them.

Onto the lighting.. one of the best things you can do, as cobaltdream suggested, is devour anything bagginsbill says (he honestly is a Poser god!). His VSS thread has a lot of useful lighting info in there, though 30+ pages is a bit much to read through at a time. His advice on gamma correction is invaluable though, and worth the search. Especially if you don't want your results to turn out looking muddy. The gallery I linked to was rendered in Vray, where it is, frankly, very easy to get good light setups. WAY easier than Poser, but ho-hum. HDRI/IBL would be a good means of getting some "overall" lighting, and then you could have spots/infinites for the special effects, like back/rim lighting, colours, etc...

sites.google.com/site/bagginsbill/

You can go to his site for his IBL generator and Environment sphere. I haven't used them, but many others have (search for the threads here) and many users have had very good results.