New budget gaming build

Hello guys.. I'm new to both this website and building PC's, or anything PC-related for that matter lol.

I live in the Netherlands, with  a budget of around 650€. (700 tops)

Should I really try to build my own PC, or are there actually some good sites out there that sell reasonably-priced (budget)gaming PC's?

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I ran across this website http://pc-samenstellen.nl/intel-game-computer?tab=configuratie#samenstellen

Dutch website, I know. What it offers is;

 

CASE: Cooler Master K-350 Advanced 3.0 (red/blue/green)

PSU: RS-600-ASAB   [600watt, 86% eff]

 CPU: Intel Core i3 2120 3.30GHz 

Cooling: stock

  
Mobo:MSI H77MA-G43 
 
 
 
RAM: Corsair Vengeance 8GB DDR3-1600 Dual-Kit 
 
 
Storage: 1TB Satalll harddisk 
 
 
optical: random DVD RW  drive
 
 
 
GPU: AMD Radeon 7770 1GB 

 
and all comes with a 2year warranty. Wooh! :P
 
Total price: 
€ 642,00
 
 
 
So. I realize this thing looks kind of pricey for its specs, but I'm a complete and total noob at PC's, and wouldnt know how to build one. Would I really really be worse off buying this rather than building my own one? Thoughts? ^_^

.. and somehow the last few lines dont feel like having space between them. Sorry for that. I'm sure you'll be able to see what it says, though :P

Same build my friends did and they love it so I would do it. Buying computers pre built is even more expensive 

the fun thing is, is that they will build it for me, so thats win-win =P

This also brings up the question:

 AMD Radeon 7770, or gtx 650ti?

ive just got my 650 and the performance is amazing for the price! i recomend it highly!

Joepvdstaaij, THe GTX650ti is faster then the HD7770 but it should also be higher priced.