The front three speakers are the most important, so focus your listening on those speakers. You pretty much need to start from the very beginning, round up a set of your favorite CDs and DVDs, and start visiting stores and trying things out. Once you've listened to a few speakers, you should have a better idea of the type of sound you prefer.

With white van speakers, the specs are false, so I wouldn't put any value on them.

If you decide to go with bookshelf speakers, just make sure that they are capable of extending down to the crossover frequency used in your receiver (usually around 80 Hz). Small cubes like the Bose systems cannot extend that far, but most decent bookshelf speakers can do this. How far down the bass needs to extend will depend on whether you intend to buy a subwoofer, and what your preferences are. In general, floorstanding speakers have deeper low extension, but they are also more prone to compromised imaging, cabinet resonance, and uneven tonal balance in general.