As somebody just approaching the end of their first year I know a great many people who were in your position and chose either mac or laptop. I can happily tell you now you'll be fine either way. The extra cash people spend on the mac definitely shows (they don't go out as much) but they're still defending their purchase so as long as they're happy I guess it's fine. People with windows laptops are also happily working away with few problems and also benefit from our universities IT system being windows 7 based.
I have a powerful desktop and a small, cheap, laptop for in uni that, together, just about matches how much you're planning to spend on a mac. being able to run any program (game :P) instantly on a massive screen with 5.1 surround while still being able to access the internet and whip up documents with relative speed when I'm out is just perfect imo. If I could change this set up though I'd have gone for a tablet instead of a laptop. This is about the only situation in which I could advocate shelling out for one :P
In summary, which ever you go for you don't need to worry about it being the wrong one, although as a student you should be seriously considering saving money. £500 is more than I'll ever have at one time for the next 5 or so years.