Install iTunes on your new computer. (2)
Authorize the new computer by clicking on the iTunes menu: Store----->Authorize Computer
It will prompt you to sign in to iTunes. Sign in as normal.(3)
Plug in your iPod.(4)
On the left hand side menu, right-click (or control-click, if you have a mac) on your iPod's menu. Select the option, "Transfer Purchases." (5)
Alternatively, you can select from the iTunes menu: File----->Transfer Purchases From iPod.(6)
This should copy your purchases into iTunes.
If you want to copy all of your music into iTunes, either use iDump, or use your iPod to do it using Apple's method. http://support.apple.com/kb/HT1329
Hope that helps!
Edited by gforce422, 02 November 2008 - 03:15 PM.