Why doesn't my home computer recognize my ipod and my work computer does They both have XP and itunes on them?

I am not sure but as I know iPod has technology to assign your player to one particular PC. If you will try to update or upload new MP3 from different PC (I guess by first time you have uploaded MP3 from your home PC) it will erase any existed files and only after this it will upload anything (it's some kind of synchronization).