I was told that my right front wheel bearing was bad by a Goodyear tire dealer. I bought new ones and when I went to put them on, I found that the wheel bearing nut was loose - I could almost loosen it by hand! So, it probably wasn't bad, but I was going to replace them anyway because my Thunderbird, which I bought about 2 1/2 months ago, had 144,000 miles on it and they were probably the OE ones.
If you do buy new wheel bearings, I'd stay away from the ones they sell on eBay - I bought two of them because I could get them both for the cost of one at AutoZone or Advance Auto. But, when I was sliding the one on the spindle, the cap that covers the bearings popped off, exposing the bearings and grease. I popped it back on, but I just don't feel good about them, now. I'm about to replace my entire front suspension (new upper and lower control arms, tension strut bushings, etc), so I'm going to buy new Timken wheel bearings for it.
It's possible, but probably not likely, that you have a loose wheel bearing nut, too. Those nuts are supposed to be tight, too - I think Ford specifies something like 188-254 ft-lbs. And, you're supposed to replace, instead of reuse, the wheel bearing nuts. I put my old ones back on (I applied blue Loctite to them), but only because I'm replacing the wheel bearings again soon. I got new nuts at the Ford dealer (about $22 a piece).
I also had a terrible knocking sound in my front suspension when I'd go over bumps that made me think something was going to fall off the car (that's why I was at the Goodyear dealer) - it turned-out that my front sway-bar end-links were totally shot. I replaced them and now my suspension has been almost completely quiet since! Those could very well be causing the noise you're hearing!