I'm not an attorney, so take anything I say with a carload of salt. The software available (either online or in a retail package) is pretty good for simple wills, leaving belongings to family and friends, and omitting beneficiaries. If you want to set up a trust of some sort, I'd have a lawyer draw it up, or go to the trust department of a financial institution. But for designating dispersal of your assets, they're fine. Most are very much like the tax software many people use, in that they go through a series of questions, and your answers might bring on follow-up questions. If you have an attorney acquaintance, you could ask them for half an hour of their time to review it. Now if the value of your estate is over the Federal estate tax exemption (now over $11 million), or if it might bump against your resident state's exemption, or if there is a family-owned business of some value involved, it might be best to get professionals involved from the start.
As far as a power of attorney, they have a wide range of options -- from very limited ones (eg: to give somebody the right to represent you while on vacation in a specific matter) to general ones in case of incapacity. And the same is true of health care power of attorney. Again, you might feel more comfortable having an attorney review the documents, but probably no need for them to draw them up -- as they're doing that work with software similar to what you'd buy off the shelf, and that hour or so that you'd be inputting data is an hour you'd be talking to the attorney, and he or she would spend an hour or two inputting the same information.