replacing graphics card

just wondering if it's possible to replace the graphics card on this product?
the specs say there's slot occupied, so can i take out what's occupying it and replace it with a better one?

 

That PC has integrated graphics, therefore that slot is very unlikely to be occupied. You can replace the GPU with a better one, but be very conservative, the power supplies in such systems are weak and not capable of powering high-end graphics cards, and they are not replaceable with anything other than the same model.

 

which GPU would you recommend?
and do you think the current specs are good enough to game with?

 

Absolutely not, 6150SE graphics are terrible for playing games with. I would recommend, based on keeping that weak PSU, that you go with something like a 9500GT. It won't be awesome, but it will get the job done, so to speak.