Good call on the infinity's - decent performance at a decent price. To keep your system simple but effective, you could also try a new CD player with something around 45 watts x 4 channels. You'll be pleasantly surprised that a powered CD player can make decent speakers sound good and acceptably loud too. User preference comes into play here, so find a cd player that is user-friendly for you, and listen to a variety of speakers before you buy. Try to select a speaker that has a fairly high sensitivity rating (90dB or higher) to help you get the most volume out of a limited supply of power.
Good luck!