I want to buy either a 13 inch MBA or MBP for university soon. I don't use any heavy software, just Office, web browsing, that kind of things. I can get both models at a good price from a local retailer and I'm leaning towards the Air for the portability and better screen. However, I can only get the Air with 4 GB of RAM (for the 8 GB, I'd have to order directly from Apple which would make it a lot more expensive). Would that be enough for the laptop to last a few years under light use or should I opt for the Pro and upgrade RAM myself?