Mac Laptops work ok but there is no marine/navigation software available for them, apart from an old version of MaxSea that you can find if you do a search on Google. Unfortunatly the marine software market if very small and the proportion of Mac users is even smaller so I guess its not worth the effort of the software people.
If you have got a fast enough Powerbook you can run Virtual PC and get most of the software working fine, though a little slow it is usable and connecting the GPS via a USB to Serial adapter works as well as it does on a PC.
