[jnorion]

As long as the two operating systems aren't accessing the folder AT THE SAME TIME (which they won't be -- either you boot into Windows or into Linux), you shouldn't have any issues. Really, it would probably make life a lot easier to set up a third "data" partition that both access, and put all your stuff on that.

But anyway, back on topic: I'm using the free version (2GB) of Dropbox and, as others have said, it "just works." It's fast and easy and has been incredibly helpful for moving things between work and home, and for viewing files on my phone.