A year ago, if someone had told us that a 15-inch notebook would be lighter and thinner than most 13-inch ultraportables, we would have called them crazy. Yet, Samsung has done just that with its new Series 9 15-inch. This $1,499 system weighs less than 4 pounds and is just a hair over half an inch thick. But thinness isn't everything: Inside that svelte chassis is a super bright display, Core i5 processor, 128GB SSD, and 8GB of RAM. Are we looking at the future of mainstream notebooks? Quite possibly.