If the memory stick is big enough, yes. But if you have 50gb of music and only an 8gb memory stick, then no.
Best bet, if you have a large music collection, is to get an external HDD, and copy the entire iTunes folder (as mentioned above). What you end up with is a mirror copy of your iTunes Media Folder, containing all apps, music files, video files, ringtones - basically anything you have in iTunes. You also have the .itl and .xml files, which are what iTunes uses as it's database. So in the event of your laptop going wrong and you needing to reinstall or whatever, you copy back the folder from the ext HDD to the My Music folder, open iTunes while holding down SHIFT (or ALT, can't remember) and it asks you if you want to create a new library or load up an existing library > choose existing and then navigate to the iTunes folder, select the itl or xml file and presto - you library is restored as it was prior to the crash/reinstallation.
Obviously, you'll need to keep an upto date back up, otherwise it will only restore to the backup you have, so if that's 6 months old, you won't get a back up of anything you've added or deleted or changed in that 6 month period.
And to be honest, unless your library is tiny, disc is a bad idea. CD holds max 800mb, DVD max 8.5gb (there were higher capacity DVD discs, DVD10, DVD14, and DVD18, but they weren't very popular and I don't think many drives support them)