Yes, I'm feeling a bit better about it now!
I'm going to play around with the values next week and try to optimise the performance even further. We're upping to 10GB of RAM in the server next week so I should be able to increase it even more.
SHMMAX was the only problem still outstanding. I'm going to try doubling that figure and then increase the Shared Buffers accordingly.
There are so many variables to consider when upgrading it's almost like starting all over again!
I'll try the ipcs-m and ipcs-ml commands when I get back to the office and report back. hopefully this thread will be useful for others wanting to optimise postgres performance.
Thank you so much for all of the replies to this post. Without you all putting in the time this project wouldn't be so successful.
Matthew
