Hey,
what maxinexus said is true, and yes reference boards are more or less the same. The quality in parts can differ, and the warranties differ depending on manufactures.
Sapphire makes very good AMD cards, you should take a look at some of their non reference cards.
Asus also makes very nice cards. However I would not go with PowerColor, they had issues some time ago, and they don't have the best cards.
I would go for a Sapphire card, although Asus, Xfx, Gigabyte, and many other brands also make very good cards.
Any of the hd7750's should work with your motherboard as it has a Pci-e X16 slot.
What power supply do you have? The hd7750 is a light card and doesn't draw much power, but its good to make sure you have enough.
Hope this helps!