Well, I've got it basically working, but you guys will laugh when you hear what I did
I built a new kernel (220.127.116.11) but I used hazmat's config as a base to start from. Then I compiled the NVidia graphics drivers by hand, but I edited one of the .c files.
In os-interface.c there is the following code on line 980:
if (err < 0)
nv_printf(NV_DBG_ERRORS, "NVRM: cannot write-combine 0x%08x, %dM\n",
start, size / (1024 * 1024));
I commented it out.
Anyway, /proc/drivers/nvidia/agp/status now says:
AGP Rate: 8x
Fast Writes: Disabled
And my screen updates (opaque window moves and such) are much faster. The few OpenGL screensavers I have on the system are much smoother when the settings are cranked up, and everything APPEARS stable. I have no "write-combining" in /proc/mtrr, but I don't know what that's really for. Either way, this is WAY better than PCI mode!
I'm busy installing the copy of Quake 3 Arena I bought a few years ago for $0.99 now.
(That was probably the best piece of commecrial software I ever bought for less than a buck...)
Anyway, thanks for all of the help, guys! I'm going to send a summary of what I've tried (and maybe even a link to this thread) to firstname.lastname@example.org
and see what they have to say about it.