Steve has the right idea, but he fails to mention the most important issue, which is: does your house have a concrete slab foundation? Having lived with one, this factor is very obvious to me. The reason it is so important is that with a basement or crawl space under the house, new waste lines can be run with little difficulty. HOWEVER, with a slab foundation, the line must be run outside the house (clearly not an ideal configuration), or else the cement floor must be broken up and then patched over the new drain pipe.
This is the real issue, and your question > is entirely dependent on its answer.