Sage
Sage
Istar
Troubadour
AurorI use Scrivener and am immensely happy with it.
Writers are all over the map with what software they use, but I am not convinced Word is well suited to the task.
Myth Weaver
Auror
TroubadourMost anything can work.
Myth WeaverI'll probably end up getting Scrivener when I'm ready to start actually writing and not just focused on researching and resource gathering.
Dreamer
AurorIf you are thinking of taking that plunge anyhow... consider that it's also a good program for keeping track of your research... I've got photos stored for locales that "inspire" description for writing in the book. That way you can stick research and ideas you know you'll use into the program so when you start writing, you won't have any downtime transferring stuff into it... if you would use it for such things, of course.
Sage