If the Falklands want to stay British, they should damn well stay British. As a nation we have a pretty good history of letting nations go their own way this last century (although admittedly it's cos we ruled so many in the first place :D) so if the Falklands wanted to go Argentinian, they'd just have to ask. They don't, and so we have a duty to defend them.
Without wanting to drag the thread down, if it came to it, at least we'd be defending one of our interests for once. But I doubt it will; they'll just have to keep beating us at football and rugby instead.