Re: Mac or Windows?
I use all of them. Garageband, iMovie, iCal, Facetime, iMessage, Safari, iTunes, OS X Mail, etc. They all work together in some ways and with my iPhone synced to the important bits, I've got everything with me all of the time everywhere I go. There's simply not an easy way to do this on my PC.
I'd say my biggest chunk of time is spent in Garageband. A huge portion of my hard drive is dedicated to sound files, plug-ins, loops, saved projects, etc.
Now, before you say "Fruity Loops" I've used FL before and it sucks. It's a complete mess and they should be ashamed for making it. And unless the paid alternatives are less than $15 (The cost to buy Garageband from the app store) they don't really count as alternatives.
17" MacBook Pro
2.3ghz Intel i7 // 8gb RAM
The older computer
2.53ghz Intel e7200 // 4gb HyperX // EVGA 9800 GTX 512mb // Win7