That's the right way, at least American-wise. What gets confusing for me is this sort of thing: "My 72-lb 'cat', who really looks more like a giant porcupine, just had a heart attack." Now, I think the comma in that case goes outside the quotation mark (after 'cat'), but then again maybe it doesn't. Every time I type something this way, I stare at the keyboard for a while, agonizing. Maybe someone can clear this up.

Vida