Drive Train noise

I have a bad, bad feeling I know what this is, but thought that I would share it- I have a regular road speed noise from the front of the car. With the car coasting, I can hear clunk, clunk, clunk from the front. Speeding up- the noise speeds up. Engine on or engine speed makes no difference. Turning left or right makes no difference. I suspect a gearbox/diff problem. Has anyone else had this problem? Just how major is it? Is it possible to fix without doing a whole gearbox rebuild? Can I just live with it? The rest of the car is fine. Windoms are REALLY cheap here in New Zealand, so I don't want to invest much $$$ in the car.
And no, its not a tyre, brake or wheel bearing noise. Help!

Transmissions don't go clunk. They either move the car, or they slip.
Check the CV joints. If one get's damaged pretty good, they'll click all the time. Check the axle's connection to the front hubs.