With the laptops you hav picked out, 6GB RAM is more than enough to run the applications you use.
Overheating can be down to a number of things. The Processor getting extremely hot and the fan having to work harder than usual to cool it down. With Laptop's its extremely important to use it on a flat surface because then the heat that the laptop gives out can escape, if you have it on the bed or something then heat can't escape and therefore is being forced to stay inside the laptop which can mess up the important components inside and can sometimes cause your laptp to blow out completely.
The i5-2450M is a very good processor. It has a maximum clock speed of around 2.50GHz which is faster than the average laptop. This particular processor offers built in Overclocking which can increase the speed to around 3.10Ghz. However if this is done, its very important to keep a close eye on the temperature because if your not careful you can actually destroy the processor.
6GB of memory. In one descripton, this is alot, even for a PC. You will be able to have many applications (Internet, iTunes, Chrome, VLC Media player, FM and even more running at the same time and your performance will still be good.
500GB+ HDD is a massive HDD, you can hold thousands of songs, movies & games on a 500GB+ HDD, even more so on the 750GB Model.
Graphics card depends on whether a) the laptop already comes with a good Graphics card or b) If you are bothered about the graphics or not. However because FM focuses more on the data side of things, and rarely spend a long time in a game, then a really good Graphics card wouldn't be nessessary, If you are playing a game, for example, Flight Simulator X then you will obviously want a decent graphics. Graphics all depends on personal taste.
For me, personally, if I was going to buy one of those laptops keeping in mind of Uni and FM and other things. I would buy the first one. The HDD is bigger, and it looks like a overal good laptop, the onboard graphics aren't too bad either.
