Thank you very much again for all the great feedback
OK. Seeing as you asked so nicely and it's not like I have re-invented the wheel with these shots here is a break down of what I did.
So using the 600 rule. Which is 600 divided by the true focal length of the lens you are using to get the maximum exposure before stars begin to trail noticibly in a print. As I mentioned before if you are not running a full frame sensor then you need to apply a crop sensor factor to the lens to get the true focal length. So my camera is a 60D using a Tamron 10-24mm at 10mm for these shots. Now the 60D is a crop sensor with a crop factor of x1.6. So 10mm times 1.6 = 16mm true focal length for my setup. So 600 divided by 16mm = 37.5 seconds is my maximum exposure length. Mike is right that I did bring it down a bit for these shots so I shot each frame at 35 seconds. So I had 35 seconds to gather as much star light as possible. My Tamron 10-24mm is a F/3.5 lens so I shot wide open at 3.5 (I would love a wide angle F/2.8 or better). The 60D has an ISO range up to 12,800. I shot these at ISO 5000. You obviously need a camera that can handle these sort of ISO's without too much noise. The 60D is ok but I dream every day of a 5D Mk II (the Mk III is as yet unproven for me). Then it is all down to your Photoshop skills- levels, noise reduction, colour balance, saturation, etc. It took me about ten minutes to take these shots and it took me about 6 hours off and on over two days to get it the way I wanted.
Hope this has been useful. Thanks again for all the great feedback
Cheers
Greg