know a good sturdy old laptop?

i suppose to avoid sand it should also be fanless, so probably a pentium m 900mhz-1.2gz max

You could go for the IBM x series (in the x31 range). Those were supposed to be solid.

E.g.: http://cgi.ebay.com/IBM-Thinkpad-X31-1-4ghz-Wireless-XP-Pro_W0QQitemZ160075031174QQihZ006QQcategoryZ140083QQcmdZViewItem

The X31 and T40 are both great, unfortunately they have fans. I read somewhere that the 1gz Thinkpad X40 is fanless, and that so is the Dell Latitude X1, although both of those are far out of my price range. I'd even settle for a PIII if it had decent battery life, no fan, and an outdoor-readable screen; but I think I may be able to wire the neurofeedback to be independent of a laptop at all, which would be ideal for these conditions. Any other hardy but ancient laptop suggestions anyone? thanks

I would continue to explore the IBM thinkpads. I've had a few used ones before, and in my experience, they are very sturdy.

the g3 (white) ibooks are super reliable, very sturdy, and can be found for under 500 bucks on ebay or even used in computer stores.