I had an old 1986 BMW 320i that made a similar noise to the one you describe - fair enough it had about a quarter of a million miles on the clock, but anyway, it turned out that it was the suspension bushes that were gone. Had to replace the whole arms but it curedthe problem. If you jack the car up a bit once side at a time and then skae the wheel that's off the ground to see if there's any play in it. If there's a lot it could point to the problem I suggested. The only thing I could say though, is that it'd be pretty unusual for a car with 25k on the clock to have it's bushes go already..