Wheres the Unix option?

Or the Both option?

I use Linux (on PC) and Windows XP, but I do have a spare machine at home with Win98 on it for my old games

I use lots of flavours of Linux, but typically its MandrakeLinux 10, RedHat 9, Ubuntu (a truly excellent OS, go get it and try it!), Kubuntu (thats Ubuntu dedicated to KDE, a happier friendlier interface than the typical alternative of Gnome) and plain old Debian because you can compile code by default from the shell *sighs*.
Its also worth mentioning that if it was a question of superiority, youd have to select your qualification criteria very carefully. The massive market share in PCs could suggest that PCs are far superior, but this is more likely to be because PCs have always been cheaper than Macs and seen as a less professional option and have also been much more widely available. I think that, in all fairness, the systems even out. They both have advantages on paper over the other. If you want to produce professional graphics then use a Mac. If you want to write programs or play games then use a PC. If you want to free yourself from a captialist world then use all your old PC parts and install Linux on an Cyrix 300 with 64mb of SD RAM like I have
Interesting: with the move to an x86 architechture for Macs, Gentoo Linux has already been booted with generic video drivers and a customized kernel on a Mac! This could mean many things... the future is going to be one of Macs coming into the mainstream market because more and more hardware will become compatible for MacOS. I just hope that Apple makes the right choice and sells MacOS for PCs... if they dont, someone else will port it and Mac might go the way of the Amiga - killed by software piracy.
*edited to make it much, much shorter*