The nForce wasn't really their IP though; it was AMDs. The original Xbox was in prototype phase and consisted of an AMD CPU and AMD chipset with some Nvidia IP for the GPU. Intel comes along and offers a PIII variant for really cheap. Part of the deal that Intel struck was that there can't be any AMD logos on the box, but they don't haven enough time to change out the chipset whoelsale, only to switch out the FSB. So Microsoft pays AMD to licence their 7XX chipset to Nvidia, so now it's all IP properly owned by Nvidia. For whatever reason, there were no restrictions on Nvidia only being able to use this for the Xbox, so they continued updating and releasing that genetic line of IP as nForce.