Linux VS Windows hosting solutions?

I realize that a lot of people will always live and die by their choice in operating systems, hardware, cars, game consoles, and caffeine enriched drinks but from the perspective of a person hosting their site in a shared environment does Linux(Apache) offer superior performance compared to Windows(IIS)?

I'm working on a site now, nothing to be excited about mind you, and using a hosting provider that only does Windows based hosting. I've talked to a few friends and gotten the speech about how Linux is superior from at least one while others didn't seem to think it mattered.

Is there really a difference?