Laser printers are not low-wattage, they're power pigs. Some may use up to 1500 watts.

I would not call laser printers and hair dryers low wattage devices. There is a chance of poor wiring, but what is most likely happening is that the sudden inrush of current is actually making the voltage dip for a split second, thus making the lights dim a bit.

Perhaps you have a bad connection somewhere in the circuit and then you would have to look at all the wirenut connections. To find out if you have a problem, get ahold of a high current device like a 1.5KW electric heater and plug it in near the printer. Measure the voltage at that point, then unplug it, get another voltage reading. I would say the difference should not be much greater than about 8 volts. If it is, you will have to trace back all the wiring to find where you are getting the drop.
To explain, if you have #14 wire in a 15 amp circuit, the ohmic impedance is 0.25 ohms/100 feet. Let us say you have 100 feet of wiring to the point in question, then a current of 15 amps should drop about (200*15*.25) 7.5 volts; much more, you have a wiring problem.

Impedance is the vector addition of (inductive reactance + capacitive reactance, whose sum is Xnet) and resistance. Never heard of ohmic impedance. Curious, what's your definition of ohmic impedance?

"Impedance is the vector addition of (inductive reactance + capacitive reactance"

Impadance is a complex number formed by the real portion (plain old DC resistance) and the reactive portion (inductive OR capacative).
It is typically written as Z = R + jX. Z is the impedance, R is the DC resistance of the circuit, X is the reactive portion, and j is sqrt(-1).
The magnitude of the impednace is sqrt(R^2 + X^2).
X is often a function of frequency, and for circuits that operate at more than a sigle frequency the impadance is rarely a single constant value.

Very good, Brick. Now what's ohmic impedance, as quoted by joeplumb?

Bigbird,
FYI, ohmic impedance, R is the resistance, R to a DC voltage, E that satisfies ohms law
R=E/I
If the source votage is AC, then ohms law is
Z=V/I
where Z is the impedance which has three components, namely
ohmic impedance,R inductive reactance XL and capacitive reactance, XC and I is not in phase with the source voltage, V.
Now the total impedance is the vector sum of (XC-XL) and R; XL and XC are opposed and their algebraic sum, X=XC-XL,the reactance is at right angles to R so the combined impedance, Z Is the square root of the sum of the squares of X and R as Brickeye pointed out.
My usage was for the wire impedance which for 60 cycle has negligible reactance so it is primarily resistive. and equal to R.