Less competition on the PC means more PC games by other publishers and indie game developers.

I recently installed Ubuntu 11.10 on my girlfriend's 3 year old laptop. It was incredibly slow! Even after reverting to the regular Gnome3 shell, it still felt very sluggish. She was obviously disappointed and wanted to switch back to Win7. I was able to convince to try Linux Mint 11. First impressions: much faster than Ubuntu, the interface felt familiar to her, the start menu is intuitive. One drawback however: her laptop's battery life is noticeably shorter on Mint than Ubuntu, and much short that on Win7. That was almost a deal breaker. Anyway, Mint is very nice, I would definitely recommend it over Ubuntu since it is faster, the interface is more intuitive and feels familiar to a windows user. But Funtoo > Gentoo > Arch > * ;)