I think the University at Buffalo, about 10 minutes from my house, has one of the fastest supercomputers in the world. It's in the top 100 as far as I know.
I'd get a laptop only because I have no need for a quad core, or 4 gigs or ram. I just want a nice computer, and I could get one of those really nice laptops that go for like $5000 starting with the 21" screen.
I would bribe Intel to give me a lifetime supply of engineering samples along with ASUS for motherboards and whatever RAM company with new RAM. Along with nvidia and ati for video cards. Of course I would ask someone to make a personal 3 stage cascade for the cpu and another one for SLI/CF for the video cards. Now with this, you can have new tech all the time