There are some games (Not only games) that depend on the Mesa Library and maybe upmi have installed mesa to resolve some dependences. I think that is not Linux faults but Nvidia's, because of the way they distribute the libs. I am no Guru too, so correct me if i'm wrong. Im using MDK since 8.0. I was a BeOS user before. Long live to Linux.
BTW: My Name is Helmer (Hammett is my QW & Urban terror nick. It comes from Kirk Hammett - I was a guitar player too, till i was 24 years old