The title pretty much says it all. I know that A' + B' = (AB)' is the basic transformation needed to do so (at least for NAND gates), but whenever I apply this I feel like I'm doing it wrong. For example:

C' + AB' + A'BD'

Here's what I did:

I took - C' + AB' - and made it into - (CA'B)' - 

which reduced the problem to:

(CA'B)' + A'BD'

Which further reduced down to:

((CA'B)')'(AB'D)'

Is this the right way to do this? Also, why is this form sometimes wanted? It seems more complicated than the original form.