Depends on how much mileage the bearings have seen and how well lubed they've been.
My 65k mi. bearings look like brand new. Just degreased hubs last weekend. The wear is almost entirely shown on the splindles, not the bearing surfaces or races.
Bearings are cheap. Only around $60 for all four. They come with new races so you should use those as well. Make sure to heat the hubs (250-300 in oven) to remove the old races and put the new races in the freezer for a while before installing.
Grease is cheap so you might as well get the good synthetic Valvoline, Mobil 1, Redline CV-2, Neo, etc. stuff. If nothing else, you should repack the existing bearings and hubs while you're at it. Replace the rear grease seal as well.
Here's some good brake info. Go to the Brake link.
Tech Info.