I'm thinking of buying a Macbook to replace my Laptop and running Windoze in a VM (I need it sometimes!). Haven't quite worked out the differences in models, but probably a 13" Macbook Pro with 8GB. However, there seem to be 2 types of these - the 'new' one and the other! With a noticable price difference. What's the difference between them? And if I get the one with a HDD is it simple to swap for an SSD as this may be cheaper than buying an SSD one? Thanks.