Recently I moved my iTunes music collection from my business laptop onto my private desktop pc. This pc running XP SP 2 has a USB 2.0 card. The iPod did connect and directly disconnect again. Googling around showed me that a quite some folks had problems, but there was no definite answer to solve the issue.
Yesterday I bought a cheap FireWire card with VIA chipset. Installed it, connected the iPod and it just worked :-)