FWIW, I have read some pretty uncomplimentary threads regarding the Geforce 2 MX PCI concept. Apparently, the GF 2 MX is optimized for the AGP bus and is underwhelming, performance wise when run through the PCI bus. As opposed to the 3dfx cards which are fundamentally PCI optimized, hence lose very little going from an AGP to a PCI version of the same card. Don't remember the links or the boards, and then again it may be just 3dfx propaganda.
Chuck