need help with right wheel bearing replacement

I have a 1999 ford explorer EB V8 all wheel drive. Recently it started making noice when driving. I think its bad right Wheel Bearing, I took it to the shop today and they also think its bad wheel bearing. They want over $400 to replace it I though that was a lots. How difficult is it to replace the wheel bearing? Do I need special tool to do the job. If this is something that I can do my self what auto part (technical name) would I need. and how much would this cost. Thanks