I'm not an expert on this stuff but there are programs that can make the dvd small enough to fit onto a single layer disc. I'm not sure if these discs work in all DVD players though. Most newish dvd players will play both + and - DVDs (what you'd have if you used a single layer burner) but some older players won't play one format (or maybe both?).
Someone else (or a google) will be able to answer this better than me.
I've never had a good experience with a celeron. I would advise to stay away from them.
Cheaper they may be, but if you look at Cost VS Performance... it's not worth it.