get one. doesnt matter how little it is (preferably for all your most important applications like the CS5 suite, and other cache intense, high processing functions). if you are doing video, graphics, animations, 3d work, editing, stop playing around with a spinning disk, and get a solid state drive into your rig immediately. For people who are not on the constant upgrade bandwagon, and are satisfied with the four gigs or ram and dual core processors, dont spend money on a new laptop. get an ssd. get an usb external drive. or if you want to get maximum space for cheap, but not take the speed hit of being off your motherboard, get a caddy that replaces your optical drive with another solid state drive or sata drive.
There is a reason people seem so impressed with the mac air’s performance.