I have been a long time user of e-Sword (alongside BibleWorks) and cannot recommend it highly enough. It is a free Bible study software program that rivals many that you would have to pay for and is better that most. This program also makes basic word studies a breeze and has been of great use to those in my congregation to whom I have recommended it. In fact, they often tell me that they love the layout and how user-friendly the program is. There is not a very steep learning curve with this program, so most anyone can catch on to it quickly. But with its recent update to version 10.4, an already great program has gotten even better. For those interested, here is the rest of the list of updates in the latest version:
New Find on Page button located next to the Search button on each view's toolbar. This Find feature makes locating content easier on large articles, such as those in many commentaries, dictionaries and reference books.
New User Files Location field in the Resources dialog (under the Options menu) for customizing where you wish for your user files to be located. This is very convenient for setting up with backup or synchronizing programs, such as Dropbox. Initially these files will still default to your "My Documents\e-Sword\" directory, but now you can easily change that!
Fixed Editor issue where it could possibly give a formatting error and not save the changes.