I use Windows XP PRO Corp. SP2 simply because it's what I was given when I brought my first set up nearly a year ago. For me it's slick and does what it should. I'll use Vista when there's no other choice.
I have downloaded a Linux OS but haven't set it up because I don't know to yet. Although when i'm ready I will install and be happy to learn the world of Linux.
I use FireFox as my main web browser. It's faster and slicker than IE. And I like the free add-ons that are available too. Thats my reason for using FireFox.
CoolEditPro is brilliant and it was free. It's excellent wave editor and mixing suite are well easy to use. Even though I have Cubase I don't feel the need to use it over CEP.
Reason 3 is fantastic and easy to use when you get the hang of things although a basic knowledge in electronics will make it easier to use. I don't use Logic because it's Mac only but would like to. From what i've seen it is pretty good.
My twin PSU set-up hasn't been criticised yet. I have a case big enough for 2 PSU's and I had one lying around doing nothing so I decided to power the Mobo with one and all the Drives with the other. I have benefited from a more stable overclock because of this. Nothing wrong with single PSU set ups but the twin will give me the power to water cool in the near future.