You didn't say what year, but I'm guessing something 1st generation. I replaced the front bearings on my 04 three different times. The first two was with cheaper non-OEM bearings. They all failed after a few thousand miles. I replaced them with OEM bearings and they've held up fine for the past 15k miles. But I agree with PHM, don't replace them just because they're old. I only replaced mine because they were extremely noisy and were leaking grease.
One way to see, or hear, actually, if your bearings need replacing, is to drive medium speed, maybe 30 or 40 mph or so, and safely but suddenly pull hard to the right, then do the same and pull hard to the left.