You'll find that the i5 will draw less power than the i7 because it's clocked slightly lower and it's physically a dual core processor (with hyperthreading, which gives it 4 threads like a quad core) which means longer battery life. Less power also means less heat, and as you probably know, heat is the enemy--especially in a crowded laptop that may actually be sitting in your lap some of the time. Just don't cover those exhaust/intake vents! Less heat also means less chance of hardware failure over time. I actually have my turboboost disabled to keep the heat down and save on battery life.. I don't notice a difference.
As far windows based performance, for your uni work (I'm assuming uni is short for university), either processor will work just fine. You would never be able to tell the difference in day to day use unless you went to encode a 30 minute 1080p HD video and put a stopwatch to it, in which case obviously the true quad core i7 with hyperthreading (for a total of 8 threads) will out-perform the i5 (4 threads). If you put a stopwatch to the time it takes to open microsoft word, you better hope you have a quick trigger finger because you're looking at a difference in milliseconds.
For performance in gaming, it varies depending on the game. Some games will rely a little more on the processor than others, but if you're not going to be playing the latest and greatest (Skyrim, Crysis 3, The Witcher 2), then you're not gonna notice a difference because you're gonna be at 50+ FPS with either processor.
If you have the option, definitely invest in solid state, even if it's just a 32GB solid state cache for your hard drive. It's the BIGGEST performance boost you can get for your computer, hands down. Mine was an extra 50 bucks, but everything I do in windows is near instant. I boot to desktop and connect to my wireless network in 11 seconds flat.