I've always heard Perpetual motion machines defined as " a machine that once set in motion (implying someone/thing starts it) will stay in motion until such a time as parts wear out"
Anyhow, accepting that definition of a pm machine will allow you to view an atom as such, since it continues in motion until it wears out. Same with the universe, etc.
PM is a joke. Sure, you can play with magnets and get a shaft spinning, but try hooking up a generator to that shaft and draw current. You might get a little, but as the draw increases, it puts up more and more resitance to the rotation, eventually canceling out the spin.
Your overbalanced wheel is much to the same effect. In a gravity free enviroment, using frictionless (or near frictionless) bearings, you could possibly cause a wheel to spin for a incredible amount of time. But how do you plan on drawing energy from this thing? Turn a generator, maybe via gear and chain or belt and pulley? Perhaps a direct shaft mounted on the wheel?
It will bring the spinning motion of the wheel to a halt, if whatever provided the initial energy to spin the wheel up to begin with is removed. Sure, you might make a little power, but not enough to continue respinning the wheel, and, power a 2 bedroom house.
Anyhow, the attempts at PM using wheels weren't completly wastefull. Want to see a modern day version of a spinning wheel? Rip the engine out your car and check out the flywheel. The engine's purpose, basically, is to spin the flywheel up to speed. As you disengage the clutch, the flywheels rotation is transferred to the transmission, which, through various gear ratio's outputs to the wheels, and moves you down the road.
A pottery table is another example of a flywheel in action. A simple foot pedal spins it up to speed, allowing the person to work on the pottery. After a short time, the wheel must be sped up again. By the person molding the pottery, he/she is removing energy from the system, doing work, and slowly bringing the wheel to a halt.
So, it took me all that to say, even if you do get an overbalanced wheel (could you define this "overbalanced" thing) working and spinning, exactly how do plan to harness usefull work out of it?