Oldest that I still have: AMD Phenom II X4 965 BE (unlocked to 6 cores) with SATA2/USB2 only and Radeon HD 6770, 'rust' HDDs only (KDE, of course)
I had EeePC, just commented on YT day or two ago:
"I had Asus EeePC (Atom/1G RAM - unfortunately it was stolen from me by ACABs). I run Lubuntu/LXDE on EeePC, and I used to ctrl+alt+F[n] to switch to tty, start another X11 on :1 and then from TWM/xterm ssh to my FreeBSD desktop and start Lumina DE on FreeBSD which worked great even on Linux X11, so I had nice graphics terminal to the FreeBSD which I could use laying in the bed; how I used that EeePC was actually "single boot, multiple OSes" use w/o virtualization and actual "OS hopping" with just a single keystroke" /q