I am moving to the bush in Zambia Africa next yearn and need a reliable computer for regulkar use. Will be using Skype a lot, putting together vidio presentations, manageing pics, and taking classes online. Service contracts mean nothing to me since we are living in the middle of no where. Thus needing a well built compute that can withstand 100"F temps...living in a hut...with dust. soooo what do you think? I will have around 700.00 to spend. (looking hard at Lenovo)
Regardless of the brand, there is no guarantee that any laptop will handle such conditions. Have you looked at more "rugged" laptops that can take a bit of a beating? I'd probably go with the Lenovo myself. If you do, just try and keep it clean (i.e. the fan ports) and as cool as possible (I know that it is easier said than done). Enjoy your time there by the way, as it is a lovely place and the wild life is incredible.
If your willing to consider other brands think about Asus, they've gotten higher reliability ratings than pretty much everyone. Pricing is also usually better than most for any given configuration.
Laptop reliability may be your biggest threat, if the conditions are what you state then you may be looking at overheating issues fairly quickly, I would not go with a top of the line CPU in the unit (since each line has a base model you might be ok at a midpoint of CPU). I'd skip a discrete GPU unless you think you will really need it, it will add quite a bit of heat. Also make sure to have a backup drive.
Even though you have a budget of $700, I would probably go for something other than a thinkpad or Inspiron. I would get a toughbook. They have been used and tested vigorously. The military uses them in that sort of climate (I.e. Iraq or Afghanistan) and they haven't had trouble. They run i5s without discrete graphics, and come in multiple levels of ruggedness. Have fun in the bushes! Hope you can decide.