Yea, you don't need the disc. The disc just has the latest versions of those programs on it when your iPod was made.
If you have music on your iPod still and want to keep it, then download
yamipod which will let you copy your music from the iPod back onto your computer, so that you can put it into iTunes again. Note though that you should do this before running iTunes; when you first run iTunes with the iPod connected it'll ask if you want to associate that iPod with that iTunes. Since iTunes at that stage will be blank, it'll wipe your iPod!