I think that sleeve will work very well. Have you checked out the one by booq? It's the sleeve i'm getting, the 12" version, but i've linked the 14" for you to check out. Few dollars more for the booq though.
The difference between this & their Vyper is that the PowerSleeve also functions as an independent case. There are times where I stick my PowerSleeve (I have the 15") inside another bag where it functions as a sleeve, while other times I use it as the only thing I'm carrying. When used alone, it can also fit the power brick and a Palm (or iPod) in the front pocket and a couple of folders in the back pocket.
Very comfortable to carry and lightweight.