Thanks for the reply Dr Byte.
The tutorial I was referring to was the original one, in post #1.

I'm worried about corrupting data by converting tables so I may start by converting a couple of small tables and wait for a week or two and if there are no problems, do another couple of tables.
It will take a while but hopefully I won't screw anything up!

If you have any better ideas I'm all ears :)

Thanks again for your help