Delete your Linux primary partitions and make an extended partition. You can make as many logical partitions as you need, inside that. All my Linux installs are in extended partitions, even on Windows-less machines.
Glad to hear NvAGP got you fixed up.
Re: NvAGP and Mandrake. It's not a Mandrake-only problem, it's a problem with the management at Nvidia. They are downright paranoid about realeasing ANY specs, docs, or code, so it took many months of begging and pleading to get the framework needed to get NF/NF2 working in kernel AGPGART. Nvidia kept saying 'it works with NvAGP, STFU and go away', apparently totally oblivious to the fact that an ever-growing group of people DON'T use Nvidia cards! Shocker!
Anyways, Nvidia finally gave in and released the stuff needed to get NF2 and AGPGART working just a month or three back. It's now in the kernel, but the distributions out there aren't using the newest version of the kernel, so you'll have to wait a release or two, till everyone gets a 2.4.21+ kernel on their default install. Then NF/NF2+AGPGART works just fine.