So you've got money to blow, your budget is around the $200 mark and the question is, what do you buy? After looking at the results it's easy; both at stock and overclocked the GTX 460 is hands down the card to get if you're looking for the highest amount of performance.
Now if noise is something that you're worried about, we would still recommend the GTX 460; not because it makes less noise but because it makes the same noise but offers more performance. Power draw is important? At idle the cards perform very close, at stock clocks the GTX 460 draws a little more power and when overclocked it draws a good bit more than the HD 5830 but it offers more performance. Under 400 watts also means that just about any power supply is going to run the card.
Dollar for dollar, the GTX 460 can't be beaten by ATI. Throw in the fact that the GTX 460 also offers CUDA and PhysX it's just a killer product. The HD 5830 has been a bit of a black sheep for ATI; its partners have never been all that happy with the model because it's never sold well. It's going to sell even worse now since we really can't think of a reason to buy the HD 5830 over the GTX 460 unless you wanted a budget Eyefinity setup. Even then, the HD 5830 isn't going to push the FPS at a native Eyefinity resolution and if you wanted to just run three monitors off a single card there's cheaper ATI options.
Even though the HD 5830 can almost give the modestly overclocked GTX 460 from MSI a run for its money, a stock GTX 460 would probably be beaten in some situations but overclocking these days is a) very easy and b)if it's too hard most companies are offering the GTX 460 with such big overclocks out of the box.
NVIDIA threw the GTX 465 to a pack of wolves and let it eat the model alive when they released the GTX 460. They ultimately sacrificed the model because now it's kind of a hopeless model because of the GTX 460 price and performance.
When the GTX 470 and GTX 480 were released I think there was a big sigh of relief coming from the ATI camp. Let's be honest; long delays and performance that didn't deliver at the level people had hoped meant that ATI didn't have to do much to the HD 5850 and HD 5870 to convince people to buy it over the NVIDIA counterparts. Ultimately they did nothing, which gave the GTX 460 a chance to come in and compete in the midrange segment and ATI needs to do something if they want to continue to sell strongly at this price bracket.
How does ATI combat the GTX 460 and the $200 price bracket then? The ONLY way is to drop the HD 5830 completely and make the HD 5850 cheaper. The 5850 is priced at around the $280 mark at the moment though, so there's just no way that ATI can give the model the price drop it needs without hurting the value of the products around it.