Hum,
>>I'll have to open the box up and have a look
Yeah, best to double check (use a mirror to see - but if you are over 11 years old then just undo the screw holding the card in, and look for any retaining slider at the base at the opposite end holding it onto the Motherboard and ease it out of the socket. It should just be as easy to slip it back in again - don't use any force.)
The main modern-day cards (there are just two, nvidia and Ati) usually have the make printed all over the graphics card...