Did some testing today with a PC containing an ECS P6BAT-Me v. 1.1 Socket 370/Slot 1 motherboard (Via Apollo Pro chipset).
Installed the fastest CPU I currently have in my collection via a Slotket - a Celeron 1.1GHz and installed 512MB RAM. I had a HDD with Windows 2000 installed on it, cloned from another PC with a similar chipset. Graphics card is a GeForce 4 MX 440 AGP8X version, using the 43.45 drivers. Also updated to the latest available BIOS from June 2000 for proper detection of the HDD I'm using and it also correctly identified the installed CPU.
Performed some benchmarks in Windows 2000 and wow does this thing suck! Tried several versions of the Via 4-in-1 chipset drivers, as well as tweaking various BIOS settings & Windows settings etc, but this thing still peforms atrociously and 3DMark 2000 often gives out garbage results like "1" or "2" 3DMarks, whilst 2001SE works fine but shows underwhelming results.
Going to experiment some more tomorrow with different driver versions for both the VIA chipset & GeForce card, as well as testing different graphics cards. I'll see if I can improve things, or give it up and put this PC back to being a PII-era system with it's original Rage 3D Pro graphics card.