Are all of your music files currently on your iPod? Has your XP computer crashed and those files are inaccessible?
It makes a difference. There are many tutorials on the web for how to simply move your files from one computer to another. You have to deauthorize your XP machine first, install iTunes on the Win7 machine, and then follow the steps that Apple suggests. Here's their tutorial link:How to use your iPod to move your music to a new computer
However, if your XP machine has crashed, been infected by a virus, or for some other reason prevents you from deauthorizing your old computer, and all you have are the files currently on your iPod, there is a way:
Download iTunes 9.0.2 from this site: Apple iTunes download
You will need to know if you have the 32-bit version of Win7 or the 64-bit version, as there are two different versions of iTunes for Win7, depending on which bit version you have. The link for both is on this one site.
Follow this help file for setting your iTunes to synch manually: iTunes for Windows 9.0 Help
I'm suggesting this because for some reason when we tried to auto synch our iPod after following these steps, Windows continually crashed. Once we manually synched iTunes, crashes no longer occurred.
Plug in your iPod. It will be recognized by iTunes, but because you have set it to manually synch, it will not attempt to auto synch, and since you haven't deauthorized your account, iTunes won't see anything there. If I recall correctly, the window will appear blank.
Watch this YouTube video of exactly how to get your music off of your iPod. Then, watch it again, pausing it while you follow the steps: How to transfer songs from iPod to computer for free
Keep in mind that the YouTube video instructions are for Windows XP (as far as setting your machine to show hidden files and folders). It is slightly different in Windows 7.
These steps worked for us, as my son's computer was infected beyond recovery with a horrible root kit virus (at least more than I wanted to work to repair it). He had all of his music on his 8 GB iPod, but the virus prevented us from accessing any files on his XP machine. We got a new Windows 7 machine in October, searched and searched to figure out how to get his music on the new computer, and finally figured out this method. He's been enjoying it ever since.