Jimmy, welcome to Axiom. You sort of have the ohms/impedance relationship backwards. Yes, connecting speakers in series increases the ohms, but this results in more resistance(impedance), not less. Since the resistance is greater, the amount of current flowing at an instant in time is lower because, following Ohm's Law, current equals voltage divided by resistance. Since the voltage at that instant is the same(isn't changed by an ohm difference)the higher resistance lowers the current. Power is the result of voltage times current, so the power used will be lower and the effect on the sound will be that it's less loud at the same volume control setting.
The opposite result occurs when the speakers are connected in parallel and the ohms(impedance)are lowered. The sound will be louder at the same volume control setting, but this isn't necessarily all good. Since the current will be higher the heating effect on the amplifier will be greater, and depending on how loud and how long this goes on, the amplifier may start to overheat and its protective circuits will temporarily shut it down.
If you have four speakers and a seven channel receiver(which you haven't specifically identified)you shouldn't limit yourself to listening to them only in stereo. If the receiver has a surround mode such as DPLII you should connect two of your speakers as side surrounds and listen to 2-channel material in a more realistic surround fashion.
