Do I have to re-wind my yarn into a ball?

[slugmom]

Another question - I got all these lovely twisty skeins (hanks?) - the long ovals twisted upon themselves. So pretty. But do I need to re-wind each one into a center-pull ball before I knit? Will it get all tangly if I don't?

I hope that's not too silly of a question. Nearly all my knitting experience is on cheapie general store yarn.