Your 160G iPod Classic just won't work with iTunes on Windows 2000. Mac is urging everyone to upgrade to at least XP, and boosts the XP or Vista sales for Microsoft with this step. It is quite opposite of Mac interest. They should allow as low versions as possible to use iTunes, so people would sit on their old systems instead of buying up Microsoft softwares, pushing down Mac average...
It would not take much to allow Windows 2000 users to use 160G iPod Classic, but Mac is working against us, who want to stay on this reliable platform as long as possible. XP is a mess and Vista is not ready yet for serious work, so we are in trouble.
Just return your 160G iPod Classic if you will not upgrade to XP for this one MP3 player. You will not be able to use it on iTunes.
The player will work with third party softwares like Anapod Explorer and alike, but you are running the risk of losing Apple support for your iPod if anything happens to it, and of course, you will lose all the work that you put into organizing your iTunes songs and movies.
Check-Mate.