I plan to order a Macbook Air tomorrow when they go on sale. My problem is I can’t decide whether to go with the base model with 258GB of SSD storage and 16GB of memory or upgrade to the model with 500GB of SSD storage also with 16GB of memory. If I get the basic model, I will need to buy a hard disk or external hard drive. I should be able to get something cheap on Amazon, but do I really want to enter dongle town.