You would need a computer that would be able to handle your choice OS?. While it makes sense to find an OS that will meet the requirements of the PC, there is still a need for a suitable PC. Obviously, this should only be done on computers you have permission to replace the OS from what was there. Many Linux OSes can run on machines that are 15-20 years old. This will breathe new life into these systems, and give something to work with.
If you are choosing to buy a computer exclusively for installing Linux, I will recommend the following requirements:
- Mid Range x86 CPU
- 16GB? of memory
- 128GB storage
Also, I will consider an SDXC card reader. This card reader will be able to work with SD cards of up to 2TB. This could be essential if you want to have a hardware that you can move files from one PC to another. While I do know there are thumb drives, I personally think SD cards make the most sense since they are smaller.