I bought an AMD A8 with an 6990d gfx then not thinking about it bought an 7750hd 1gb card My question is what would have been a better option going with the 7750 or buying a 6690 card and run crossfire with the APU which I can do.
If you can afford to keep the 6990 cool then go for it. Even though 7750 belongs to newer series, it belongs to the entry level card of HD 7000 series, while the 6990 is the prime of 6000 series. But one thing: a dual gpu tends to perform a bit lower than the same cards in crossfire/SLI. You may opt for the lower priced Radeon R9 280X or maybe Radeon R9 290 budget permitting.
About HD 7750, it is a really good card with a very good performance per watt and performance per dollar values. But the card is not meant for serious gaming.