Been looking for a planetarium for the PC, had a go with Sky Globe a few years back, found this free one "Stellarium", runs in OpenGL and its graphics are pretty good, might be worth downloading if you like the occasional look at the stars.

I see it has plugins too and one of them can send commands to a telescope to find things in the sky, that's how I read it, so it could be used by serious astronomers too, saying that they probably know about it already.  

I would check it has Hubble deep sky objects. Most have them embedded as standard these days.
They have Messier objects, what about NGC?
Do they charge for the 210 million extra stars?

Looks good though.

Yeah it is good, shows a novice like me where things are.

Don't think there's any hidden costs, I cant find any.