Is this pumpkin ready to harvest? And variety?

I'm a big pumpkin lover and have never tried growing them before. The exact name of this variety escapes me - I'm sure I still have the packet at home - but its Jakarta, or something along those lines. The skin is a grey-blue-green hue. I planted early as I like to cook with them. I just don't know when they are ready to be harvested. Any thoughts? This variety is doing even better then the standard orange I have growing - so much better, in fact, that two plants have almost taken over my garden. Any suggestions are appreciated thanks!
J

Here is another one. Hard to gauge size in the pics but each are about 7 pounds or so.

Winter squash are usually ripe when the skins and stem are hard and dry. Usually when you cannot dent them with a fingernail. They get tastier when stored and some of the excess water evaporates. Looks like a Jarrahdale http://davesgarden.com/guides/pf/go/61933/

Farmerdill, that's it! Jarrahdale

Then they aren't ready yet as they're still dent-able with the finger nail. Really like the way these look. Thanks so much!