1. The iPod isn't linked to your Apple ID -- iTunes would be. You should be able to use your old ID and update the email address. In fact, you can probably update the email address online via Apple.com
2. Take a look at this support post of mine -- in particular, para. 8. That will describe how to find tools to move your music from your iPod back into iTunes... but don't do it yet...
3. First, read this summary post of mine about synching problems with iTunes 10.5 (and possibly 10.6). If you don't have your library and iTunes 10.5 already on your laptop, I would install 10.4 instead (there are links in the post). Let's get things working with a known reliable version of iTunes before we add another variable to the mix.
4. Once you have iTunes 10.4 on your new laptop, connect it to your Apple ID and authorize the computer. You should then be able to download purchased content (if you're the type that buys from iTunes).
5. At this point -- I strongly suggest backing up your iTunes library (the .itl file). Get a USB drive larger than your iPod, connect it to your laptop, and assign it a fixed device letter. I suggest M: for music. Then follow the instructions in my summary post on moving your music library to an external drive, and move it to that device. Consider then backing up your music library.
6. Exit iTunes. iTunes is normally not running when you copy music back from the iPod, but follow the instructions from your utility.
7. At this point, use the utility you found to copy the music from the iPod into iTunes (make sure it works with 10.4).
8. Once this is done, follow the instructions on your utility to make sure everything it working.
9. Once everything is working, back up your .itl itunes library again and save it someplace safe. If you ever upgrade itunes, you should be able to go back to 10.4 at this point if the newer version doesn't work.