Even though Nvidia is still in litigation with Microsoft over Xbox pricing, it has said in this ZDNet article that they will only make AMD chipset motherboards because they don't want to pursue an Intel P4 bus license.
The company also plans a follow-on to its nForce chipset, which works with Advanced Micro Devices' Athlon processors but not with Intel's Pentium 4. Huang said the company will continue to focus on chipsets for that market, rather than pursue a license to work with Intel's chips.