Yeah I see a huge market in the Linux camps and Mac camps, not. I would be willing to bet that the numbers of Ms users VS linux/MAc users is very lopsided.
Besides the absurdity of segmenting your market into "Windows" and "Everyone else", consider World of Warcraft (WoW). With supposedly 8 million concurrent subscribers, it has set a new record for percieved market of the MMOG genre (previous record was the roughly 3.5 million players who played Lineage). The new expansion pack for WoW, Burning Crusade additionally set a record for fastest selling videogame. Significant differences between Lineage and WoW? You can play WoW on a Mac. It is true that most Linux users want as most SW as possible to be free (free as in free beer, not free speech although most Linux users will tell you it's the other way round
It is. Otherwise they would just be pirating Windows (and whatever games they wanted to play) much the same as most other Windows users do.