The first question you will face when assembling a home audio or theatre system is whether to go the route of separates or a receiver. Years ago, this question was easily answered based on budget. But thanks to Rotel's "balanced design" philosophy, breaking up is no longer hard to do. Of course, if you do not have the space for several pieces of equipment, then a receiver may be your only option. You will also need to take the power requirements of your speakers into consideration.
Theoretically, separates provide better sound. Consider that a receiver has three components all in one box: a tuner (radio), a power amplifier (several if it is a home theatre receiver), and a preamplifier (for volume, tone controls, etc). That's a lot of noise-generating circuitry going on in one box. By having separate components, each one is designed to handle one task, with their own dedicated power supplies, and without interference from the other.
This also makes it easier to upgrade or repair a component. Ordinarily, receivers cannot be upgraded, and if the tuner section breaks, you must bring the entire unit in for repair, creating system down time. Yet if you have a separate tuner which breaks, it can be sent for service but you can still enjoy the remainder of your system while you await its return. And if you find a better tuner that strikes your fancy, changing to the new model is easy, as opposed to living with whatever is built-in to your receiver. Your power will also be limited to your receiver's rated amplification, unless you add an outboard amplifier.
Having said all of that, receivers have come a long way. It could be argued that if you invest in a very high quality receiver, such as Rotel's RSX-1560, you could approach (but not match) the level of separates. A receiver will also require less interconnects and may prove easier to use and faster to set up.
In general, if you have the money and the space, seriously consider separates. Otherwise, buy the best receiver within your budget. There is a half way solution to the above dilemma: an integrated amplifier. An integrated amplifier, such as Rotel's RA-1520 or the improved RA-1570, combines the amplifier and preamplifier in one chassis (the user may add on a separate tuner if desired).