Durock or Hardi for shower wall backing?

First off, mortar is number one. But applying mortar for walls is definately not for an amatuer. As for your choices, I quit using Durock, Wonderboard, Crumblecrap (whatever name it goes by now) a long time ago. I use nothing but Hardibacker for floors and recommend it for counter tops, tubs and shower wall substrate. it's just a superior product and easier to use IMHO.

For installing the backerboard it helps immensley if you make sure your walls are plumb and the enclosure is square. Run a straightedge horizontally across the studs to check for any that may be bowed as well, and correct that beforehand.

Learned it the hard way and I will second the opinion above.

Colbyt