First, what width rear hub do you need? road hubs measure 130mm and MTB hubs are 135mm. In real life, I don't think there's any real differance in how strong the wheel is using either width hub, so it all depends on what fits your frame.
Having cracked open and rebuilt a lot of Shimano hubs, I'd stick with LX (MTB) or 105 (road). Going up the product line doesn't make the wheel stronger. I also like the '08 Tiagra hubs, (all of the '08 Tiagra parts are good)
Good spokes are a must, use and either Velocity or Mavic rims and you'll have a strong set of wheels.
Honestly, I'd check EBAY for a new set of wheels first.