Strange moaning from under the bonnet?

[double_tap_that]

Ok so its not the wife, but under the bonnet, when im in traffic or doing about 20mph i sometimes hear this sort of moan/groan sound, its not on the wheels as it does it when stationary.
Im guessing it may be the alternator bearings? ish??
Or someone else had a similar problem?
Cheers

[GrandadMonkey]

Could be, or the auxiliary belt, but see my reply to your other post.