I was just wondering that do I have to do something for my iPod which is only used in windows, so it would work in Mac? I know this is a noob question but I only want to make sure before I buy a Mac.
What SmartIndianKid said, plus this small, oft-overlooked caveat:
A Windows-formatted iPod cannot receive a firmware/software update from iTunes in OS X-- only from iTunes for Windows. I ran into this little problem just the other day. It'll still sync to your Mac without a problem, though.
If you're planning on keeping your old PC around, keep iTunes on it and use it for updates only.