how to use one iPod with two computers

apple: http://docs.info.apple.com/article.html?artnum=61675
Rachael Smithey: http://macs.about.com/od/ipod/a/itunes_dedicate.htm
ipodhacks.com: http://forums.ipodhacks.com/archive/index.php/t-441.html

Conclusion: Set iPod to "manual mode" or use third party soft instead of iTunes