Its very unwise to delete the songs from your computer. You would be just as stuck if your iPod were stolen or damaged. I also *strongly* recommend that you backup your iTunes library. Even if you still have the CDs there to rip from again, ripping a hundred CDs is a tedious task, so you don't want to have to ever do it again. Back up your files.
By deleting the songs in iTunes, the next time you sync your iPod with itunes you're essentially telling it that you want to delete those songs.
I hope you have a backup of your iTunes library, otherwise you'll be importing all those songs all over again. If you do have to reimport your CDs, then make sure you've got an Internet connection up and running so iTunes can get your track-names automatically.