Yes, that will be the media card. You may want to get a larger card, depending upon now much music you have within Itunes / or want to have on your phone. They (4GB,8GB cards) are quite cheap nowadays, from eBay.
Another method for getting iTunes content onto your phone is to use the Blackberry Media Sync program - just google it for the download link. I use it and it works well.
Hope that helps.