Unlike Dave, I don't get to trash pick for a living, I have to live with amateur status. But many of my machines were trash as well. My current shop machine is a Frankenputer that I have running Ubuntu Linix. As soon as I find another monitor or two, I'll have a machine set up in the barn.
I don't bother with a roll up keyboard myself. I suggested it because I set one up where I volunteer, which is a full blown boat shop, making wooden boats and other wooden things. I don't make enough sawdust in my own shop to worry about it. I just blow it out with compressed air every now and then. But let me take this opportunity to preach keeping your CPUs clean. And not just shop machines. No matter how clean you think you're keeping your place clean, think again. And laptops are a particular problem, as it is difficult, at best, to take apart. I find the best way to clean one is to know where the "exhaust" is for the cooling system, and "back flush" with compressed air.