Prime Time- Although I earlier suggested getting an iPad, I also have a Win7 laptop for work, and a Mac at home, and have my bias for one over the other. As pointed out here that a "rugged" design laptop, probably will only prevent shock, and not really protect you against water and salt corrosion. I would have to agree with that. Most electronics on boats fail from water, corrosion, or lightning, not from being dropped.
So what to choose? This is what I tell my clients... First settle on the application that will fit your need. There are free sailing/navigation applications, and then there are applications that cost several thousand dollars, and all prices between, although Most are sub $200 or over $1000. Each program is different, better interfaces, more or less information, ease of use, etc. Remember that your expense isnt just the laptop, but also the software, and possibly peripherals that you will need to connect the laptop into the systems on your boat. Most software manufactures will offer a demo version, or a 30 day trial period. You dont need any great laptop to try them out, heck just put them on your pc at home, and just see if you like the interface for them. When i was first trying them out i put them on my laptop, and used them while driving to work, that gave me 10 chances to use it before i got to the boat each weekend.
I am sure that this group will be happy to post a list of applications. Here are a couple, that I use, that work fine for coastal cruising. All under $100.
PolarView (mac or pc)
GPsXNav (mac)
SeaClear (pc or Linux-which can be run on a mac-although I haven't done it) -Free
I know you said you wanted this for racing, and I cant help you there with software, most of the people I help are really just out coastal cruising, but an iPhone 3Gs or iPad (either the 3G version or one with a GPS attachment) and Navionics or GPS NavX apps work really great. Plus you can throw them in a ziplock freezer bag (or two) to keep the moisture out. (I have quite a few military friends who did that in Iraq and Afghanistan)
From your remark above that the Panasonic is pricey, I assume that you dont have $5K+ (latptop + software) to spend. The great thing about most of this software is that 1) you dont need to have the latest and greatest fastest laptop 2) it doesnt take gobs of memory to run it (which could be an added expense over the base price of the laptop). Until the monitor finally gave out I used an very old IBM laptop. It weighed about as much as my anchor. I really like the new netbooks by Aser, Asus, HP, and Dell. They are all small and cheap, and run Win7. Since they are cheap, pick up two, since one will die at some point. The down side is they are small - the screens are like 7". Moving up from here are the Windows laptops. As I said earlier, and if price and screen size is a big deal, get two year old one off eBay, that will be your best value. It may run Win7, but most likely XP (stay away from Vista, like its the plague). On the filp side are the Apple Macs, and the iPad. These are more pricey, but have a much more stable OS, and the battery charge lasts 25 to 30% longer than a comparable PC laptop, which is important. I think battery thing is why I see so many cruisers using them, where power is a premium.
As John N points out you can run PC software on a Mac... There are several ways of doing this, some free, some require additional software ($). I do it with my home Mac (but this is another discussion). Either way if connecting to peripheral systems in your boat, it may not work
HTH.
