Ok that's an interesting point now. Personally I see it a bit different: 4890 (or GTX275 as well) to GTX285 are ~10% speed increase overall. But 300 to 400 bucks is a 25% price increase. But you are absolutely right, when the price is not such a big issue you are better of with simply buying the fastest chip out there, which currently comes from nVidia. I think this depends much on your personal situation. For me as a trainee, $100 is a very considerable amount.