Is this desktop good or bad for gaming?

I recently just bought a HP desktop. I didn't know what I needed to look at(specs) To know if it's a good computer for gaming or not! So I bought it anyways:/ now I feel stupid because this stupid piece of machine is terrible… Can't even play minecraft. Runs like 1-10 frames(FPS). Yeah… Bad! I'm pretty sure it's because of the GPU( AMD Radeon HD 8240) the only reason I also got it is because if was cheap (319.99) 110$ off original price. Should've known it was bad… I basically want to only play minecraft, and minecraft is a java game(yes I can run java and it works.) Is there any way to increase my FPS? Do I have to but a new GPU(I was thinking about the AMD Radeon 6450) but I'm not sure if my computer can run it! Do I need to return this piece of junk and buy a new computer? Suggestions please?! I don't really want to build my own computer because it costs Way too much!
Ahh… Miserable

Its nothing to do with the gpu. Minecraft is a cpu intensive game. First turn your video settings down. If it still lags sell the pc on ebay and buy a new one

First, return it. Sounds like you gave one of those e-series processors from amd that barely outperform a pentium 4 from six years ago.

Second, building a computer is actually Way cheaper than buying it premade. $320 will get you a great computer for minecraft.
http://www.amazon.com/...00CPLGGWS/
http://www.newegg.com/...6820313353
http://www.newegg.com/...6822236339
http://www.amazon.com/...00JAEXH48/
http://www.amazon.com/...004ASW73G/

All together, costs $320. As for windows, piratebay. It can be installed through the usb ports.