The way I see it, the processor of the Ferrari is better future-proofed because it's 64-bit, but the graphics card of the XPS2 is better future-proofed simply because it's more powerful and may even be upgradeable. The XPS2 is going to be more powerful at playing current games, but it's larger and heavier and the battery won't last as long as that of the Ferrari. That's what it's come down to for me.
For the fastest mobile (~6lbs, 15.4", ok battery life) gaming notebook: Ferrari 4005WLMi, which also happend to be fully 64-bit supported with all official x64 drivers from Acer.
For the fastest DTR (10+lbs, 17", short battery life) gaming notebook: Dell XPS
IMO I can't really recomend a 32-bit only notebook at this time. There are 64-bit enhanched games showing up and that is where everything is headed. But if you want the fastest gaming performance right now and don't care about other features then yes maybe the Dell would be nice for you. But who knows what you might want to use your notebook for for a year or more from now.