Which tile adhesive?

[Measure_twice_cut_once]

I'm tiling my bathroom floor to ceiling with porcelain tiles - do I need special porcelain/waterproof adhesive or will regular tile adhesive do the same job? I will of course be using a powdered waterproof grout. Also, should I buy ready mixed or get the powdered adhesive?

[thedoctor]

The readymixed waterproof adhesive is much easier and holds well but the powderwed grout is best.