It’s perfectly acceptable for a MAc user to purchase a PC for a specific gaming purpose, if (As in this case) it is necessary as a platform for a game that will not work on your Mac. Providing that is why you buy it, it’s no different from buying a PS3 or a Wii so you can play games that only come on those platforms.
And you can buy a PC for very little money that will run Civ3. It’s worth it to play such a magnificent game.
I played the hell out of Civ3, but CivIV is a much better game that avoids some horrible gameplay experiences from Civ3. Migrate to CivIV and don’t look back.
Civ 4 is even better if you delve into the world of mods - I’ve touted it before and I’ll tout it again: Fall from Heaven and it’s bigger, badder and hugely better but more complex brother Fall from Heaven 2 . Magic, demons, vastly different civilisations, hugely innovative gameplay, religions that actually have an impact on the way the game plays - I could wax lyrical for a long time but I won’t, just try them.