Headache-relieving maybe, but also eyesore-inducing.

Some simple, good advice for choosing color combinations is that in terms of HSB, never vary more than two aspects of a color. That is, you can vary hue and saturation, but then don't vary brightness. Or, vary hue and brightness, but leave saturation constant. Or vary saturation and brightness for the same hue. This is simplifying matters a lot but it's a fairly good starting point.

There's also this awesome site: http://colorschemedesigner.com/