would that card be able to play online computer games on the highest graphics settings without lag?
Some but not many, see the feedback tab at the Newegg link I provided.
and would i be able to put this processor http://www.newegg.co...N82E16819103851 into the system without having to upgrade the MB or the Case?
Yes but it would be a waste of a good processor in a very limited system and would not help with the gaming you are looking for without additional Ram, a suitable video card and a PSU that was capable of providing good clean and stable power.
now the other thing.... is where in the machine is the graphics card...
There isn`t one, the MB only has an onboard video chip, from your MB specs Integrated graphics using ATI Radeon 3000
when i opened the machine i seen those 2 really long black ports and only 1 of them had a "CARD" in them... what is that?
What you are referring to are the DIMMs/slots where the Ram goes and the card you see is a stick of Ram.