We've looked at turning a MacBook into a tablet computer and even written some software for you to turn it into a nice heads up display, but Instructables user mkarvonen has created a how-to that demonstrates how to turn virtually any laptop into a touchscreen tablet — so long as you have the requisite patience.
Mkarvonen's instructions only require that old laptop, a soldering iron, some wires, and basic tools to open the laptop. If you pick up solderless touchscreen, however, you may be able to avoid the soldering altogether (If you prefer). You can take things easy if you want, but the instructions also show you the harder way that involves creating a very polished end product.
I've turned my old netbook into a touchscreen tablet so I can tell you that this isn't the sort of project you want to take on lightly. While it's not particularly complicated, in the sense that you're just ripping open your laptop, removing the keyboard and trackpad, and flipping the display on top of everything else, it still comes with plenty of challenges. You'll often have to disconnect internal cables and reconnect them in ways that fit better, and chances are you'll accidentally break something incredibly small but important and have to figure out how to fix it.
Although you'll encounter some tough challenges, the reward is pretty great. Having a touchscreen tablet that you've made yourself is pretty cool and worth the few of days or tinkering required. Be sure to check out the full how-to over at Instructables to get started.
How to make a tablet pc from an old laptop [Instructables]