Thinkpad T440p.
Old, slow, cheap, yet powerful quality
This used Thinkpad was my first machine for programming and learning. It runs Ubuntu as its primary operating system. It has a 500GB HDD and 8GB RAM. The processor is an Intel I5-4300M. With these specs it gives plenty of extra time for additional planning and thinking while it boots. Over time it has gone through some modifications.
RAM & Storage
8GB/500GB HDD
Processor
i5-4300m
It features the Thinkpad trackpoint, which is super convenient for navigating the computer without a mouse. Unfortunately the normal base T440p comes with a trackpad missing the needed physical buttons, which I wanted. Fortunately a Synaptics trackpad with physical buttons can be purchased on Ebay for fairly cheap. Installation is not too difficult.
One of the best parts about this old Thinkpad has been its ability to be repaired and the bountiful supply of used parts online for cheap. I have done a lot on this machine including a complete replacement of the motherboard.