Gotcha, Cybergypsy! Thanks! I shoot a LOT of images and so I only put online what I actually post-process and want people to see.... I have external HD for storage of everything at home. Also, I shoot primarily in RAW, which definitely makes for much larger files than .jpg, and that can make a huge difference!
Even as I type I'm in the process of finally upgrading my Mac Pro to Leopard, and once I get through with all the software updates, etc., I'll then be upgrading it to Aperture 2.0. Much as I love Aperture, I don't think I'll be putting it on my MBA, as it does take up a fair amount of HD space and I wouldn't be using it all that much on that computer.
I totally adore my MBA!!! It is the best little gem!