Internship Options - Summer 2007

I am currently looking at internship opportunities for summer 2007.

How much choice do you have as to what desk you are assigned to? I want to be a trader. I will be applying within fixed income and want to be put onto a desk where i will be able to use some of the high-level applied maths that i have done at undergraduate leve

I don't want to end up in a position where i am not really using a lot of the skills that i have learnt. At interview if you state you want to work on say IR derivatives desk will they take this on board or will they just place you on a random desk...

Any thought on this would be helpful....

Obviously this is dependant on me getting an internship which will be hard in the first place.