OK... now that I am on my laptop I can reply w'ith a longer post.
I am a firm believer in the use of all available resources in Prepping.
This includes Computing Technology.
Now in relation to the OP, we find ourselves in a position where there are many ways to skin that cat.
To be honest there are very few things that a Prepper would need from a computer that a tablet or a Smartphone will not do. As long as you put it in a ruggadised case solution that is. You can easily recharge either on a small portable solar system. I personally have bought some Power Bank's for each person in the house so that they can charge thier mobile devices at need. Then we charge the power banks from solar.
My first suggestion would be to look at this as a first choice.
Now for the tasks that require more capability, we get into the use of a computer.
I have went for this due to many reasons. Here are a few.
Radio Programming
Monitoring with a Software Defined Radio
Map and Terrain analysis with the ability to print custom maps
Nautical chart plotting with GPS
Project Management Work
And a bunch of things I am still looking at.
Now to do this more intensive work. I recognized I needed a rugged computing resource. I chose the Panasonic CF-U1 as the best compromise for what I wanted. Size and weight are acceptable to me. The capabilities built into the unit are great. Even more. It is JUST powerful enough to do the things I want it to do.
Now for a DIY solution, the sky is the limit.
Can a rugged, portable and low power usage system be built? Yes.
Could it be built on a budget? Yes (Depending on what we want it to do)
To do this would require a geek that is comfortable with this level of work.
I could write out a massive amount of positives for this approach. As I said I ave been toying with the idea of doing something like this. More in line with a "Future Soldier System" wearable solution. I might at some point do this project.
So that's my penny's worth.
Thanks
All