The odd thing is that they dont even state if there is a psu that comes with the computer under tech details. I found a zoostorm that actually stated its psu on ebuyer ( http://www.ebuyer.com/340946-medion-desktop-pc-medion-1... ) and it says it comes with a 250w psu so im guessing the one you are looking at would come with a 300w psu to power the nvidia gt520.
What are you planning on doing with your pc? Gaming or just browsing?
If your not using it for games than its a fine pc for writing docs and browsing the internet but if your planning to play the latest games out then this pc isnt going to cut it.
Pros-Cheap, ok gpu, 500gb hdd, win7
cpu is garbage 2.7ghz dual core
-only 2 RAM slots on mobo this says your mobo is also garbage and will need to replace the mobo if you want to upgrade your cpu at some point.
-doesnt even state what kind of psu comes with the pc which is sketch and means its trash.
-Site doesnt state what kind of mobo which is also sketch and means its going to be low end.
I suggest either buying a pc from a website that actually tells you everything about the system and all the technical details. Or just build your own pc.
The 300 or less wattage psu that comes with the pc is probably fine in powering this pc but if your planning on adding more ram or new graphics card or better cpu then you definitely need to upgrade the psu. I would suggest Antec, Corsair, Enermax, Seasonic, XFX 80+ bronze.