With home sharing you can combine your music from your old computer to the new one.
Itunes sharing . Things may change as itunes moves cloud based. . "online streaming , downloads " for your own music etc.
Ipod sync is one way in most cases , although.
In itunes try using the File menu and transfer purchases from ipod /iphone
, to the second Mac or PC .
You my need to Authorise the computer to share your music and downloads at which point you will be asked for your apple ID and password .
Purchases on the ipod /iphone will be copied to itunes .
Sync the ipod / iphone so all music and data is current.
If you have music from a different computer , make sure it is shared with the second computer using home sharing . Once the music and data is shared across all computers and ipod / iphone , then you can remove the computer that is not being used anymore . See Deauthorize computer in the Store menu , and turn off sharing for this computer as below.
More on home sharing:
There is a home sharing option built in to itunes 9 onward . Please use Apple software update if needed to upgrade itunes to the latest version.
You can use this option to share the music and video in the home place network .
Sharing your iTunes library across computers
If your computer is connected to other computers over a local network, you can share items in your library with up to five of those computers.
While your computer is on and iTunes is open, others in your network can play your shared items, but shared items can’t be imported into others’ libraries.
If you want to import items from other iTunes libraries on other computers in your home, you can turn on Home Sharing.
You can use Home Sharing with up to five computers.
To use Home Sharing, you must have an iTunes Store account.
Sharing is intended for personal use only.
To share your library with other computers on your local network:
Choose iTunes > Preferences, click Sharing, and select “Share my library on my local network.”
Select the items you want to share.
To require users to enter a password before they can see your shared items, select “Require password” and enter a password.
If you choose to share your entire library, its name appears in the iTunes window (below Shared) on other local computers set up to look for shared libraries.
To change the name others see, choose iTunes > Preferences, click General, and type a new name in the Library Name field.
To turn off sharing:
Choose iTunes > Preferences and then click Sharing.
Deselect “Share my library on my local network.”
To import items from other libraries using Home Sharing:
Choose Advanced > Turn On Home Sharing.
Type your iTunes account name and password, and then click Create Home Share.
Using the same user name and password, repeat steps 1 and 2 on each computer.
To import items from another computer, select the computer (below Shared), and drag items from its library to yours.
To automatically import iTunes Store items that are downloaded to a computer you’re Home Sharing with, select “Automatically import new purchases from [Computer Name].”
To turn off Home Sharing:
On each computer, choose Advanced > Turn Off Home Sharing.
You can share movies; radio station links; and MP3, Apple Lossless, AIFF, WAV, and AAC files. You can’t share programs purchased from Audible.com or QuickTime sound files.
You can also find this info in Itunes help , launch itunes , use the top screen help menu , select itunes help , search for home sharing.
Alternative solution .
Note : Apple TV is the easiest way to share music , video and pictures etc on the local home network .
It basically is a HDD networked box that plugs in to the home HD TV and audio centre . Apple TV connects to a local network via Wifi and serves music and film wireless to all computers on the network or directly to the HD TV plugged in to it .
Once you are shared across all you computers and authorised , and Deauthorized if needed "if a computer is not used any more or to be sold" ..
If you have music on a second PC that is imported via audio CDs or downloads or your own music etc and you don't want to authorise the other computer .
Just burn an MP3 CD/s and copy the music to the itunes folder by adding the music to the itunes library , check import settings in itunes preferences .
Be aware of copyright on music and other MP3 or video content , also convert WMA "Windows media audio files" files to MP3 or AAC for use on Mac if moving files from a PC , this can be done in the itunes import settings , choose a WMA file in the itunes library window , use right mouse button on the selected audio file and select Make MP3 Version or convert to MP3 AAC , the setting is made for conversion / import in the itunes preference , please ask if help is required.
I hope this helps .