I'm a small-scale operator and I don't know what a VPS is but, If you want to get your data out to the world, something like Xively is surely the simplest way to go. If you don't want it out to the world, I don't see the point of using ethernet at all. I really can't comment on your choice of frequency, it would depend entirely on your needs. Fifteen minutes would be useless to me, ten seconds is OK. I still don't think you need to save the stuff up and then feed it every fifteen minutes. There are rules about upload rates and quantity and I believe ten seconds is the maximum rate. I still use Xively but I understand Grovestreams is better and you might look at that. I haven't gotten round to defecting.