is it purchased music? if so you have two ways now.
1)just plug in ipod and transfer purchased music
2) use the new share feature in itune 9.0+ (current version is 9.0.2, just saw the update for it yesterday)
for 1, you just plug it in and click transfer purchased music. you must have that computer already activated with itunes store though.
for 2) you turn on itunes on the old computer and then again on the new one. you must sign in for the transfer account (do this on the origional computer). once that is done, start up the second itunes and it should show your itunes playlist from the other computer under devices. run it and it will redownload all of the purchased music off the internet.
if you want to transfer music that wasnt purchased through itunes, then the only way to do that is the old fashioned way, which is with CD's... i would probably just buy a CD-RW so that way you can just rewrite over the old songs and not have to use 10 cds if your library was over 1000 songs, etc... however if you want to back it up, then you can just buy the regular CD-r's. once you write on these though, they are done...
