This is a link to the thread where I got help. I didn't know about this forum at the time. It has been stable since.
Truthfully, I have no clue whether it is using agpgart or not. I did remove something from the kernel though, APIC or ACPI can't remember which. Actually, I have had to reinstall since then and it has been stable. I'm sure it put that back. I did disable it in Lilo though. You can do that through the Mandrake Control Center then boot then configure. Just uncheck the box. Grub has something similiar.
Note, the problem that I was having was after several days without a restart. Sometimes it would go for a week or more and then die.
I recommend that you look into your Mandrake Control Center under System and LogDrake for errors after you install. The way I usually do is to boot after midnight then select today only on the right. You can have one heck of a wait if you do the whole thing. It parses 4 to 5 weeks of log. Good CPU burn in test though.
I hope this helps. Post back if not. I still got the read me from NVIDIA.