First let's talk about the HD 5570. It's not a bad model; it's just not really a gamers model unless you're talking about some 1680 x 1050 lower steam gaming. For something like Counter Strike, Team Fortress and other source based games, it's a great little option. Throwing the word OC on is a bit of a stretch, but we can't deny that the core is overclocked by 20MHz.
The HD 5570 has a market; it's not my market, but it could well be yours. It handles older games like Dark Void fine and Batman AA. It's also going to perform strong in Source based ones. The worst thing is we probably make the card look a little worse than it actually is because of the way we test our games. It's a good card, but hardly award winning.
The HD 5750 Silent Cell on the other hand is good and next to the HD 5570 it looks great. Let's just look at some quick facts; the model is double the performance of the HD 5570, yet not double the price; clearly a rarity in the video card market. The silent cooling is, well, dead silent and still throws out some seriously good looking cooling numbers. Coming off 70dB+ GTX 400 series cards, it's a real pleasure.
Most of the time the HD 5750 Silent Cell is able to handle 1920 x 1200 with max in game settings. When it doesn't a small detail change will fix it. The HD 5750 Silent Cell from GIGABYTE has everything going for it; price, performance, quality and features. There's not much more you could ask for from a mid range card.