Can i ask when you say OLD Cds and iPhone 4, Where are they now, Just on the old phone. On an old PC? After you answer these I can tell you but for sure go ahead in the meantime in preparation install the latest version of iTunes on your new PC and set it up the way you want it.
If you have the old PC by getting the iTunes music folder from the old PC to the new would also be a good start after you install the new iTunes. You can also if you have an external hard drive, Place all the music from the old PC on it if you have not, This will also make it easy to get it to the new PC.
Read these also
iTunes: How to move your music to a new computer
https://discussions.apple.com/docs/DOC-3991 - With this one just replace iPod with your old phone to the new one with the same concept.