Which laptop should I buy?

I am an electrical communication engineering student.I use softwares like Xilinx ISE, Matlab and a few programming languages.I already have a desktop which runs on ubuntu and windows.However I wanted to buy a laptop as well.Which one should I buy.I was thinking of Sony, Thinkpad, Dell Latitude/inspiron, or a macbook.I have not narrowed down on any model as far as sony and the thinkpads are concerned..Please help me out.(although I am am having second thoughts about the macbook..As I stay in India, support for the mac is not very good,Ive heard)...