I had not seen this before — Linspire apparently offering a bundle of PrBoom and Freedoom as a "Click-N-Run" package. They don't mention either up front, but the specifications page makes it clear that it is PrBoom, and it is in the package name (plus the status bar is definitely Boom-like). It looks like they are shipping the GL version.

It seems a bit dodgy the way they use the Doom trademark, and one of id's promotional images for Doom 2, and even list id as the vendor. Okay, the source code is half from id, but it doesn't contain any of id's design or artwork, so using id's trademark for it looks very suspect.