I fixed the challenge with the iPod. There are several things you can do but only one of them worked for me.

First, make sure your computer is authorized to use your music. iTunes allows you 5 computers.

Second, download one of the free songs. For whatever reason this is what fixed my problem. I suspect that when I jumped from XP to VISTA the sub directory where the music was housed changed. Hence, downloading that song told the iPod where to look.