iTunes and second PC

I have a PC to which I downloaded ITunes. To ITunes I loaded all my music CD's and as well have purchased some music from ITunes. I have just purchased a second PC, a smaller one for travelling and a second for around home. I want to have ITunes on the second PC and all my music. Do I need to open a second ITunes account? Or do I simply download ITunes to new PC. If it is the last option, then will all my music appear on my new PC as well as my old PC? I do not know if it matters but my new PC is Windows 8 , my old PC Windows 7

Hope this makes sense.many help?

Thanks!