4gb --> 8gb for $100 - YES. I would not consider a 4gb model in 2013, just for the sake of future-proofness. Yes I know that isn't a word.
Core i5 --> Core i7 is debatable. If you're doing video then yes it's probably worth it. I.e are you transferring and encoding true HD video from your camera or phone? I would like to see some benchmarks though.
If you're only surfing the web and writing documents stick with the i5 CPU.
If you want to be able to use it for a very long time I would recommend both.
If you have to choose only 1, 4>8GB of ram is a must.
I will be getting the 8GB RAM for sure, but right now I'm just trying to decide whether to get the i5 or the i7.... Why does it matter if I will be using it for a very long time?
Where's the $270 difference coming from? Isn't it only $200 and less with education discount?
I'm not sure what to do...