Cheers Todd.
I have finally got SRP working between ESXi 5.1 and Solaris and have put on Windows SBS 2011 Essentials on another box. The drives for Win 2008r2 do have a SRP miniport but it is throwing up the (unable to start) error, the Subnet Manager etc are all starting fine.
One post I came across suggested that if you have more than 2 targets then the Windows miniport will fail to start. I have 4 . I will probably have to remove a couple and then try again but after 3 painful days to get to this stage, I will leave it for another day this coming week.
I also agree, the Mellanox guys have been very proactive and helpful which is pretty rare and to be applauded.