Budget is a good place to start. Now we need to know what kind of music/sound you like? Do you like mellow, bright, tons of bass...
Do you want monitors or floor standing. You can do floor standing in the front and monitors in the rear. How much space do you have? Will you have space behind the speakers? If they have to go near a wall, you don't want rear ports. Do you want 5.1 or 7.1? 7.1 can get crowded.
A small room may require only 100wpc, while a huge room or really inefficient speakers may require 300wpc or more.
Do you have neighbors to piss off? Most of us can never have a big enough sub. The better the sub, the less strain on the rest of your speakers and amp.
I love Anthem and Sunfire gear but even they have big differences such as 100wpc vs 400 wpc and hdmi or not when buying used. Some people have space constraints and buy high powered tiny sub/s. Some people have so much room that they buy a pair of 500 watt REL subs...
Get the picture so far? Need more data...
Finally, if I had it to do over again, I would have scrapped my projector and bought a 50 or 56 inch plasma. the picture may be a little smaller but has a life of much more than 1000 hours, doesn't need a cooling fan and works well with all the lights on.
Don't forget at least a couple hundred for a line conditioner or surge protector to take care of your $10k investment.
