So, I'm going into my senior year in college. I'm a physics major working on computational physics research - lots of enormous sets of data and multi-dimensional modeling. I'm also applying to phd programs for when I graduate. I have a $1500 grant for use in my research, so my PI has told me to get myself a good computer. My laptop's light & fast, generally, but not so good at the heavier duty stuff. So: what should I look for in a desktop? Any advice on specific ones?