I came across a neat thread on another forum recently on the topic of miniature pcs on board and the consensus seemed to be that you could put one together, including monitor for less than 1000 us dollars that will outperform a laptop, and can be securely mounted in dry places. They also run on 12v. I'm not sure if it is appropriate to post links to other sailing forums though, or if anyone is interested!
http://www.logicsupply.com/product_i...roducts_id/401
This is the general idea though.