John, I don't normally get into back-and-forths with "my esteemed colleagues" and other "distinguished gentlemen" here, but I'm going to make a special exception just for you ("lucky" you!

). You should know by now that I've been more than helpful to a lot of people here and my choice of words was meant to impress upon the OP (and others wondering the same thing) the level of difficulty of what he's proposing. A simple search of the subject keywords would have revealed that and we shouldn't answer the same question a million times when the answer has been well-documented already. That results in not being able to spend that time on questions that haven't been answered adequately already. If you have a beef, start with a PM, OK?
For HackMyPiAndEatIt (one of the better handles, BTW!), John is right about not hesitating to ask questions, so if I came across as the grumpy old crank that I am, please realize that we have seen this kind of question many times before, often with the expectation that it should be a simple matter of just plugging things together and applying a SMOP (a Small Matter Of Programming). Some things are at that level, but connecting an LCD display directly to the Pi is one of the most difficult things one can undertake without inside knowledge. There is a Display Serial Interface (DSI) on the Pi designed for this purpose, but it requires knowledge of and programming access to the Pi hardware at a very low level that the Foundation has not (yet?) provided. It also requires details about the (often parallel) interface for typical LCD displays being considered that may only be provided by the display manufacturer to product manufacturers. This is often a matter of engineers not having time to do so without compensation, not to mention being more than busy working on the next generation of display interfaces.
Just out of curiosity, what was your expectation of what you were going to be able to display on the DSi screen? It's awfully small (3.25 inches) and low resolution (about 256 x 192 pixels) and it would barely be able to display text, especially in a GUI with any usable level of detail. I assume the intent is to display game graphics and that would be fine as long as anything requiring readable text beyond game output isn't being attempted. It wouldn't make for much of what one would typically expect a laptop to be able to display.