Welcome to the discussion,
Make sure your new computer is authorized in iTunes. Disable autosync in itunes, connect your ipod, right click on it in the device list and choose backup.
This will save data, pictures and settings to itunes. See what's included in this backup here:
http://support.apple.com/kb/HT1766
Transfer your purchases the same way to copy all apps and bought media from the Store to your computer.
Set up at least one contact and event on your computer to be able the merge your calendars and contacts after your ipod got wiped during the first sync.
The rest of the data can be restored from the backup you made.
Restoring:
http://support.apple.com/kb/HT1414
Music is one way only, from the computer to your device, unless you bought the songs in itunes and transferred your purchases.
There is 3rd party software out there, but not supported by Apple, see this thread:
http://discussions.apple.com/thread.jspa?threadID=2013615&tstart=0
After that, don't forget to include iTunes into your backup routine:
http://support.apple.com/kb/HT1382
Message was edited by: Ingo2711
