I use Final Draft 6.0 (they're on 7.0 now), but I actually find Movie Magic Screenwriter to be a much better program. I know plenty of people who use it.
Final Draft isn't so much the "industry standard" as it is the most prevalent, pervasive program. No one can tell the diff between a script printed in FD and one printed in MMSW (the same can't be said, however, for those printed using MSWord templates).
I know a few people who've used Sophocles and rather like it. I think Derek (dpaterso) or ComicBent used it or something similar to it once, or perhaps it was a Word template. I can't remember. I used to use a Word template but, now that I have a legit program, I'd never go back to the templates. FD is much better than any template I've ever used.
Anyway, if your friend is REALLY serious about doing the novel-to-screenplay thing, I'd second the recommendation of Writer1 that she really study up on format and dramaturgical structure AND that she shell out the money for MMSW or FD (or find it one ebay, or get a college student she knows to use their discount to get it for about $100 cheaper).