Oh I forgot to mention that enabling ACPI for nForce2 systems is not recommended for SuSE Linux. In fact, the SuSE installer kernel won't boot up (on my system) if ACPI is enabled. I'm pretty sure the default athlon optimized kernel won't either. Unfortunately you probably wouldn't know to disable ACPI unless you read their mailing list (archive).
Instead of disabling ACPI completely, I've just turned off PCI IRQ routing (pci=noacpi). Neither change solves the problem I have.

Even worse, I was hoping I'd at least get power management (for system suspend) if I disabled just IRQ routing, but judging only from the KDE PM tool, that doesn't appear to be the case.
Ref:
http://forums.anandtech.com/messageview.cfm?catid=34&threadid=1087645
As I stated in that thread, ACPI for (SuSE) Linux is still relatively half-baked. It's fairly essential for notebook PCs, but seems to create problems for desktops.
Edit:
nVidia still hasn't updated their Windows UDP, but new Linux nForce drivers were quietly released:
http://www.nvidia.com/view.asp?IO=linux_nforce_1.0-0261
I say quietly because you have to visit the nForce Driver Archive page to find them. In theory, for kernel 2.4.20 or later, their nForce GART patch will support non-nVidia GPUs, such as ATI Radeon. I might give it a try soon; last time I put a Radeon 9x00 card in my system, SuSE showed a completely blank screen at bootup. None of their documented workarounds (disabling FB text mode) seemed to work either...