Hi Mark - thanks for your help I've got it all in OK but the following may help others WITH A CARD READER.
Insert the iCN520 card into your reader (& for safety make a new card to work on)
[ie. make a new computer desktop folder,open the iCN520 card, select all, drag a copy into your new folder, remove orig card, insert new card, drag CONTENTS of temp folder onto new disc]
Open the new disc, Open 'NAVMAN'
Create a new folder - 'MYPOI' (in caps)
Open the GPS Data Team folder named 'Copy to device folder - MYPOI'
Select all and drag a copy into the new 'MYPOI' folder on the disc.
Close all & insert the disc in your Navman iCN520 and proceed as normal.
[PS you now have the orig as a backup or you can repeat onto it too]
Forgot to include - card needs about 80 meg so use a 125 meg or up