In response to Polas's post from April 26 2009 10:56PM
As with most things, "it depends." It depends on the model, the machine being level, how much laundry (and what kind) is in the washer, the spin speed selected, and the kind of floor the machine is on.
Brands like Samsung and Electrolux have put a lot of research into vibration reduction/elimination technologies. Samsung's dual-ring ball-bearing system (VRT, or Vibration Reduction Technology) cuts down on tub swaying during spin, which reduces vibration to the floor. Electrolux has a floor-sensing technology that determines the kind of floor and then bases its spin speeds on that information. For these reasons, these washers are usually suitable for second floor installation.
On the other hand, brands like Whirlpool and LG tend to have more vibration during spin cycles, and are more suitable on reinforced first floors or concrete floors.
Some companies manufacture vibration pads for front-loaders. They're basically a thick sheet of rubber that the washer stands on. The rubber helps absorb the vibration and diffuses it over a larger area, reducing the transference of vibration to the floor. They are moderately effective, but will not completely eliminate vibration noise.
Also, having odd combinations of garments in the wash (like, say, a large thick towel and a tee shirt) can cause the load to become unbalanced and that can cause vibration noise.
Or, if you put in a really big load of heavy towels and set it to the highest spin speed, that can cause vibration noise.
I say "can" with most of this because it is possible, but it also might not make excessive noise. As with most things, the full set of circumstances determine what will or won't happen.
If you're going to have the machine by a bedroom, I suggest an HE top-loader like the Whirlpool Cabrio, Kenmore Oasis, or Maytag Bravos. They make the least vibration.