i finally got my super old PC working again.
1) CPU: AMD Athlon K7 1333 MHz@1000 MHz
Due to an old CMOS battery the Board resetted all configuration to default and the CPU now only runs at 1000 MHz. But I remember that System having temperature issues at a high workload and I think I'll keep that settings for the next time. Maybe it also has advantages when debugging?
2) 256 MB DDR memory
3) Elitegroup K7S5A mainboard with SiS 735 chipset (version without integrated audio or LAN)
4) Matrox G550 AGP graphics adapter
5) Realtek 8029 based LAN adapter
6) Aureal Vortex 2 sound card
7) IBM 10 GB and Quantum 60 GB HDDs
8) LG 4163-B CD/DVD writer and Matsushita CD-ROM
9) A 3,5 " FDD drive

Booting that system up into Windows XP and seeing all that ancient data from an earlier myself has been a little bit spooky...

I already ordered the following:
a) serial RS232 nullmodem cable
b) PS/2 mouse (keyboard already is PS/2)
c) CR 2032 lithium battery for the board (but as mentioned above I don't plan to use it)
Did I forget something?
How to start then?
Basically I plan to connect the nullmodem cable to another computer, monitor the output via terminal session and try to install the latest daily ReactOS build on that machine. What terminal software and what COM port configuration is recommended?