1. Vista is the worst OS. Stick with Windows XP if you can. 2. I hear that Leopard and Vista can compete, but since Vista sucks Leopard is better because it can emulate Vista on that OS as well. 3. I don't know much about Linux

It's a good question ! Why every everyone is a good system, for example if you want do use a video softwares use MAC OS, if you prefer the system it's easy to use the best is Windows now if you prefer the system that is easy and its possible to improve the code by yourself Linux its the better. I use Linux(Ubuntu) and Vista in my laptop HP. I like to use both, Because its good to know how to use other System.

If you like linux and you are a fresh man,then use ubuntu, that will help you a lot. Based on ubuntu, you can use Mac, cuz they are famillier. Of course, windows is the most easiest system. Vista is good and stable except for its administrator operation and strange phrase that many home user can not understand

I prefer windows xp than ubuntu. Although ubuntu是免费的但上youtube时候比不上xp. Mac os never tried this before

MAC OS leaves little room for improvement. Perfect stability, perfect emulation of windows machines with 'parallels desktop' or 'VMware fusion'. Leaves no need for another operating system as long as its security does not deteriorate.