You can have a try this transfer.
It can backup all your music and videos on ipod to pc, and if you need, you can drag them into your new itunes
You can have a free trial:http://www.aiseesoft.com/ipod-to-compute…
Hope it useful to you!

You may refer to this step by step guide, it will teach you how to transfer iTunes library to another computer, it’s easy to understand and works pretty well for me. It’s safe and it will not delete your iTunes music and video.http://www.reviewstown.com/how-to-transf…
Hope it helps. Contact me if you have any other question.

When I changed my computer, I used MediaWidget to move all library files from my iPod Touch onto my new computer http://www.gutensoft.com/Utilities/Media…
It can transfer all iPod content to the iTunes on your computer, including iPod music, movies, playlists, videos, podcasts, ratings, last played, and more.
Now all files are on your new computer and iTunes, you can sync your iPod with it smoothly without deleting any files.
Just free download it to try.
For more iPod support information you can also go to http://www.apple.com/support/

>> I love iTunes, I believe it is a fantastic piece of software,but there are certain limitations that makes it slightly irritating.Just like the issue you encountered.
>> To avoid losing all my songs,my【iPod Computer Transfer】 allows me to transfer all the contents between my computer/iTunes and iPod at any time,without iTunes running.
>> It’s absolutely an awesome iTunes alternative.This is the product page on Facebook,you can have a general view of this terrific transfer.http://www.facebook.com/photos.php?id=12…
>> Sharing music is easy again, I can finally transfer all my friends music onto my computer. haha
>> You can try it for free, I think you’ll be pleasantly surprised how well it actually works compared with all the other software out there.
Enjoy,

One of the easiest ways to transfer iTunes library is by use software to copy the library contents off your iPod to a computer. I recommend Cucusoft iPhone/iTouch/iPod to Computer Transfer.It helps to copy all songs/videos/photos from ipod to computer directly and safely.
Free download it at:http://dvd-video-soft.com/ipodconverter/…
Also you can backup your itunes to CDs or DVDs.All you need are blank discs and some time.
Hope it helps.
You can keep asking on http://answers.yahoo.com or use http://www.ask.com to search more

You can use this tool to copy songs, videos, photos, playlists, podcasts and more from your iPod back to itunes on your computer. It is a fantastic itunes alternate. You can use it to manage your iPod. It won’t erase your ipod contenthttp://www.dvdtopreviews.com/ipod-copy/c…
If you are using mac os, you can try this one insteadhttp://www.dvdtopreviews.com/ipod-copy/3…
If you still have questions, contact with me or keep asking on http://answers.yahoo.com

Here is an easy way many of my friends use. That is to use this iPod to computer/iTunes direct transfer program to get all iPod songs onto his new computer and iTuneshttp://ipod-tool.com/ipod-software/jobos…
It was designed to help transfer music, videos, photos, playlists, podcasts and more from iPod to computer and iTunes. So you can use it to transfer music from your iPod back to your iTunes in a direct way. Then all files are on your iTunes, and you can sync smoothly without deleting any files.
This is easy and quick. I recommend you try it.
Best luck!
For more iPod instructions, use http://google.com