Syncing with a new computer shouldn't force you to restore. At worst you lose all media, and have to resync them from the new machine.
If you still have your old computer, just copy the iTunes folder from the old computer to the new one, then start iTunes with.... hmmm, was it option-click or alt-click on the Mac? Anyway, that should let you select the iTunes library you want to use. Point iTunes to the folder you copied, and things will be just like they were on your old computer.