I've been asked this question a lot, and have given pretty much the same answer. I want to extend this question to other more experienced people, just to put a few new practicing witches at ease.
"Do a person have to practice Wicca to be a real Witch"?
Poison, you're a bit wrong there. Wicca very much includes witchcraft/magick. But to the original post, one does not need to be Wiccan to practice witchcraft. Wicca is a religion, while witchcraft is a practice, Many religions include the use of magick in their practices, but it is not necessary to be in one to practice it.
I think the confusion comes when one confuses spellcraft with magic. Certainly not all Wiccans cast spells, many of us do it rarely if at all. However, all Wiccans use magic in their practices. We use magic when we consecrate our tools, cast a circle, Draw Down the Moon, raise energy within the circle, etc. These actions are not the same as casting spells but sometimes the terms spellcraft and magic get used interchangeably which muddies the understanding when people are arguing as to whether Wiccans use witchcraft.