@ Odion
you guys do know that a new kind of DvD is coming out that can hold up to 18 gigs of space. What more do you really need!
You are probably referring to DVD-18, Ben-Hur is the only movie I know of which used this format and was released years ago. This isn't optimal as you can read from the review below:
"The choices they had were to split it over two sides of a double-sided, double-layer disc (a DVD-18), or to split it over two single-sided, double-layer discs (DVD-9s - perhaps the most common variety of DVD available today). In both Region 1 and Region 4 they have chosen to use a DVD-18. To be honest, I'd have preferred that they use two discs, because two discs would be easier to handle, and would be more useful in the event that you had either two DVD players, or a DVD player with multiple disc capabilities. I suspect they used a single DVD-18 so they could state that they'd put the whole movie onto a single disc. Anyway, what it means is that you must handle the disc quite carefully to avoid getting fingerprints on it, and it is a little more fragile. Also, because the only label is a thin ring around the centre of the disc, it is not particularly easy to work out which side is which. It doesn't help that they haven't labelled them clearly, either - both labels say "Widescreen DVD Ben-Hur" - you think they could have added "Side A" and "Side B". The easy way to tell them apart is to look at the serial number: on the first side it ends in A and on the other in B. Still, look at it this way: DVD-18s are quite rare, so you get an uncommon piece of technology for your money."
Having XBox 360 games on double sided DVDs would mean you would still have to swap the game disc to read the other side, also you will have to watch out for fingerprints for both sides. Blu-Ray discs, apart from being relatively scratch resistant are also pretty fingerprint resistant, in addition to that the Blu-Ray laser is more scratch and fingerprint tolerant while reading your DVD collection.