Ive only had the chance to visit a Mac Store and quickly lift each but for those of you who own both, or have used both, how much of a noteiceable difference is the 13" MBA's weight in comparison to 13" MBP's in real world situations? Is it noticeable when I carry it in my backpack? On my lap? Picking up to carry around the house. I plan on taking it to school every day, as well as carrying it between my sofa, desk, and bed in my house and if its not too much a difference, I think the added power of the MBP as well as the generally nicer screen and extra storage would come in a little more handy. (I would be replacing the disc drive with an SSD if its not too difficult. Also, is it very difficult to keep my current HDD, insert an SSD into the disc drive, and transfer my OS over to the SSD? Or is it something I should leave to a professional. Thanks.