I've found that I have to do two things to prevent prints that are too dark in Aperture 3. One, click on the "More Options" selection in Aperture 3's print dialog and turn OFF Black Point Compensation. Two, adjust the Brightness slider (in the More Options print dialog) up to 1.10 rather than its default of 1.00.
When I do these two things, my prints are a near perfect match to my display.
FWIW, with Aperture 2, I had to kick up the gamma in the print dialog to 1.04 or 1.05 (from a default of 1.00) to get prints to match the display.
Also, I find it much more difficult to get matched prints in Photoshop. It's much easier to deal with it in Aperture (2 or 3).
Lastly, if I recall correctly, Black Point Compensation was turned off by default in Aperture 2. So that might explain why you are having better luck with Aperture 2 on your laptop. Also, I remember reading something about Snow Leopard having issues with Black Point Compensation. The whole issue with prints that are too dark started for me with the installation of Snow Leopard.
Mark