Standard DVDs hold 4.7GB (that is decimal GB, Windows will report the capacity as 4.58GB).

IIRC dual lkayer discs are 8.5GB. They are usually very expensive though, so it would probably be a lot more economical to use normal ones.

If you have a lightsscribe burner then you just need to buy some lightscribe discs. I don't know about the software required though - I've never used it myself.