Is a will prepared using Quicken WillMaker software legally binding?

You may have to get it notarized. Some say "it can be legally binding"

"However, the legal manual included with your software (accessible from the "Help" menu) contains extensive legal information that addresses most common user questions. Consult the Legal Manual to see whether or not it deals with your specific query."

If it is properly witnessed in the appropriate jurisdiction, it likely is valid. If your assets are extensive or complex, or your disposition other than straighforward, it is risky to do your own will. However, if it follows the requirements re execution it is certainly valid.

Each state has its own laws about executing (signing) wills and trust documents. It also gets more complicated if you are changing an old will or specifically writing someone out of your will who would normally get something if you didn't have a will at all. In those cases see a lawyer. If its straightforward though, you can use the software just fine - but sign and date EVERY page and number the pages like "2 of 5", "3 of 5", etc AND DO ALL SIGNING IN FRONT OF A NOTARY.