Please help! Dell Optiplex 755

[AMINP1]

So i am thinking of buying a dell optiplex 755/760 i dont know which tbh, here is the link:
http://www.amazon.co.uk/gp/product/B00HABDK40?ref_=cm_cd_al_qh_dp_t (most sold on amazon)
is the original graphics card it comes with sufficient for hd 1080p video playback or will i need to upgrade it?
p.s i know very little about computers

 

[popatim]

They dont list a graphics card so it depends on what they throw in it to be honest.

 

[AMINP1]

They dont list a graphics card so it depends on what they throw in it to be honest.

suppose they throw in a graphics card that isnt suitable for watching 1080p videos, what is the cheapest graphics card i can fit in the devise and how hard is it to do?