Procedure for buying and setting up a new computer
1. Find the right computer - processor, RAM, HDD, (SSD?), etc. Buy it after verifying boot from appropriate USB key.
2. Image the drive without booting from it. (clonezilla)
3. Store copies of drive image 'as shipped' in several places, in case needed for warranty service.
4. Wipe drive and install your favourite Linux (or two), LibreOffice, two or three secure browsers, email client, VPN, anti-malware, email encryption
6. Image drive again.
7. Use computer.
8. Back up at regular intervals.