My dad really needs a new laptop, and I wanted to get him either an MBP or MBA. I'd like to keep the price beneath $1500, and lower is better. He is by no means a power user, but travels a lot, so weight is a concern. Right now, he literally has a 10 year old, 600 MHz, 128 MB RAM, 4 GB HDD, 2'' thick Dell. Yeah, it's bad. I think the MBA would be plenty fast for his needs, but my only concern is with the slower, 4200 RPM drive. How slow is it? I have a netbook with a 5400 RPM 160 GB HDD, so it's probably slower than that, right? By a lot? An SSD would be nice (from Runcore or another 3rd party), but that would add another $300 to the price, and even if I got a refurbished Rev B, the price would probably be more than I'd like to spend. Any comparison numbers for the 4200 RPM drive? Thanks.