We've answered this limewire concern a few times already - yes people can change it but it's not very likely. Limewire is no where near as popular as it once once - there's no need for a 5th thread on it.
And to echo what's been said here, if someone were to break in they wouldn't both with limewire in any way shape or form. If they went after any data like your bank and tax stuff they wouldn't put it into a limewire share (I honestly didn't think it was still used by anyone) they'd take it then either use it themselves or sell it to an ID thief. Putting your stuff up where anyone can get it for free is the last thing they'd ever do.
As an aside, if you're so worried about security risks related to limewire, just uninstall it.