400 Euro gaming PC!

Hello! I need help building a decent gaming pc for around 400 euros ($518) as i have no idea what im doing, im from Ireland.

The games i would be playing are WoW, Blops2, TF2 and HoN.

If you could take a look at what you can do id greatly appreciate it :)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

http://www.youtube.com/watch?v=s6kFRalEq-M