On screen, don't forget an image is backlit, so will seem brighter than it really is. In print form the image will rely on the light falling on it. Try upping the contrast and perhaps raise the exposure by half a stop or so. On my screen it could certainly do with a bit more contrast. Hope it helps.
EDIT: I stopped using aRGB a year or so ago in favour of an entire sRGB workflow. What I lack in colour gamut for editing is absolutely non existent to the eye, and I get stunning results from pro-lab prints. Whatever space you use for your photography and editing, it must be consistent, and images for the web will need to be formatted with the sRGB space for best viewing on a website. Unless you are experienced in colour management I would suggest you choose sRGB too. You will be very pleased with the results I'm sure.
Example of what I mean here:
http://www.flickr.com/photos/amazons...es/2846003850/