The 5770 wasn't entry level, though you might think so by the boards. It was just one tier down from their high end cards, the 5870 (the 5970 was the dual GPU card), but yeah, that is not a powerhouse of a GPU now. It is quite weak, but if you play on low settings, it is likely your CPU holding you back, which both may be having some issues with heat. Laptops have that issue.
What is the CPU in your laptop?