Thanks guys it's sorted!
Tried the import from O.E source but despite unlocking hidden files the new machine wouldn't recognise the old messages on the flash disck - possibly because they were FAT format?
Read an article suggesting on XP home I needed to start in "safe mode" to be logged on a administrator to access such files. Seemed very convoluted and prone to cock ups.
So I too used the File and Settings Transfer Wizard, which worked a treat.
Now to set up my Apple Powerbook with hopefully more user friendly software!