To the TS:
A lot of people have answered the question you have asked several times over in the past, and in different guises.
What is usually important, if you just bought your camera < 6 months, upgrade your skills and lens first.
As I see you are a student, using a Canon EOS 1000D, and just joined us for < 6 months, we can't tell you what is missing in your arsenal or even in your skills unless we look at your sample shots. Maybe from there, we can at least guide you as to what you can 'upgrade'.
But if you wanna 'upgrade' from 1000D, I'd recommend something like a 7D or even a 5D, if you can afford it.
HTH.
Cheers!