If your iPod is formatted for Mac it won't run natively on a PC because the Windows OS does not support the HFS Plus file system and therefore will not see the drive. There are third party programs that will allow you to use a Mac formatted iPod on Windows. XPlay for instance gets good reviews and has the added functionality to let you copy your songs back to iTunes. Once you have your songs saved to the PC you can go ahead and restore the iPod for Windows. You can get XPlay at this link:
XPlay 2
If the iPod is Windows formatted there are a few things you can do to restore your iTunes from the iPod. If you have any iTMS purchases the transfer of purchased content from the iPod to authorised computers was introduced with iTunes 7. A paragraph on it has been added to this article:
Transfer iTunes Store purchases using iPod
The transfer of non iTMS content such as songs imported from CD is designed by default to be one way from iTunes to iPod. However there are a number of third party utilities that you can use to retrieve the music files and playlists from your iPod. You'll find that they have varying degrees of functionality and some will transfer movies, videos, photos, podcasts and games as well. Have a look at the web pages and documentation, this is just a small selection of what's available, they are generally quite straightforward. You can also read reviews of some of them here:
Wired News - Rescue Your Stranded Tunes
TuneJack Windows Only
iPod2PC Windows Only
iGadget Windows Only
iDump Windows Only
YamiPod Mac and Windows Versions
Music Rescue Mac & Windows
iPodCopy Mac and Windows Versions
There is also a manual method of accessing the iPod's hard drive and copying songs back to iTunes on Windows or a Mac. The procedure is a bit involved and won't recover playlists but if you're interested it's available at this link:
Two-way Street: Moving Music Off the iPod
