I don't have the time to read the entire thread but if it hasn't been suggested yet check out Chromebooks. Based on your needs I think this would be perfect. They're inexpensive, durable, basic and mobile which your kids will love not having to be in a certain place to learn. The boot up in less than 10 seconds so if your kids have a question it's no problem to open it, boot it and get the answer. The Samsung one retails for $249 and I've seen them for less than that. It's worth every bit of $250 IMO. If you're in the Google ecosystem it's even better because you can log into your account and there's all of your info: Email, contacts, calendar, browser history, bookmarks, music, Drive, Talk, Google+, hangouts, etc. Full size keyboard, plenty of expansion slots and what not and no HDD means no moving parts to go bump in the night. The Chrome OS is lightweight and won't have the same bogging down issues that full featured OS's tends to over time. These are really solid devices and for basic web access and about 90% of what most people do they're perfect.