Well +1 for the 5200...It is faster than the 7750 clock-to-clock and overclocks much higher...
But if you want to overclock, make sure you get a aftermarket cpu cooler...
How much do you know about overclocking? And what is the motherboard you're planning to buy along with the processor? It's because I know a lot of people who heard of Intel's overclockability but buys a motherboard that doesn't even have voltage settings and then cry wolf.
well it all depends on your budget. The 7750 can be paired with a 790gx board for really good onboard video. With the 5200 you will almost surely need a graphics card, but just based on cpus hands down the 5200.