Hey I just canceled my iMac G5 20" model order because I'm going to want the portability, and I don't really need the speed. So I was wondering whether or not the hard drive upgrade is worth it? I use Photoschop CS, Go Live sometimes, have a huge iphoto and itunes library. Just wondering if I'd see any major boost there? Also, I'm having a tought time deciding between the 15" and the 17". Both can come with the 128 mb video, which I definitely want, and have the same number of ports. So I'm just deciding whether or not the extra screen real estate is worth it? Thanks.