Well I got Simplify working again, but had a chance to play with Mojo in the interim and it's just a much, much, much (did I mention much, much, much) better app for Mac users. And not only because it incorporates, shall we say, additional functionality alongside simple streaming from remote libraries.
My friend is running the Windows Beta version on XP and hasn't had any problems with that so far, so MS users aren't shut out.
Anyway, it's well worth checking out.