Got 2 more free systems a few days ago.
Both are S478 (P4) systems.

An early P4 system.
It looks like this PC was a victim of some really noobish PC tech.
There was an (unsecured) AMD (!) heatsink which fell off the CPU (perhaps the tech used thermal paste as glue ?).
There were two hard disks. One 30GB Maxtor and a 20 GB Seagate.
Maxtor drive was working but damaged (bad sectors, maybe the drive was dropped ?). 20GB Seagate was OK.
There were 2 optical drives, both secured only with 2 screws (same story with Seagate HDD). One CD-RW and one DVD-RW. Both drives are Lite-On
Now, for the specs:
MB: Some unknown, Intel Chipset, no LAN (but PC has a PCI NIC installed)
CPU: P4 1.4Ghz
RAM: There was no ram installed (MB uses DDR RAM)
HDD: 20GB Seagate Barracuda ATA IV, Maxtor 30GB (with bad sectors)
VGA: Some Geforce 2 card
PSU: Codegen 350W (has PPFC. Looks usable to me. Modded with 3.3V 5V plug)
Case: Minitower, incomplete (missing side cover).

Very nicely built P4-era system (except for the PSU).
The spcecs:
MB: Gigabyte GA-8ST800 (SiS 645DX chipset, no LAN, supports P4 HT. Uses Japanese capacitors.)
CPU: Celeron 2.0Ghz
RAM: 256MB DDR-333
HDD: 40GB Samsung (tested, working)
VGA: Some Geforce 4 MX
PSU: 300W Generic/NoName (very light, no PFC. I think I will toss it)
Case: Midi ATX case, Missing side cover.

There’s also a Samsung DVD-RW installed.

Did not have time to test any of these systems yet. Only tested the hard disks.