Here is another nice DIY kit for building your own computer at Newegg called the "Core i7-2600K/Z68/8GB/60GB SSD Gaming SuperCombo"
it is a lil cheaper than the i5-2500k kit mentioned above, but doesn't have a videocard with it.....
this one is: 
http://www.newegg.com/Product/ComboBundleDetails.aspx?ItemList=Combo.787574   Combo cost = $ 636.99 ( then has an additional $75.00 worth of mail in rebates )
mid-tower gaming case ( this case has plenty of fans and does a good airflow/cooling job )
650 watt PSU
MSI z68 LGA 1155 intel MB
i7-2600K
8 gigs ( 2 x 4GB )  Corsair vengance Ram 1600 MHz
OCZ Vertex 3  60GB SATA III SSD
just need a Videocard ( around $124.00 to $200.00) depending on what you want or can afford, 
the OS ( operating System ) going anywhere from $89 to $140  depending n what you want  , I recommend Windows 7 Pro SP164 bit, 
and a DVD Burner  cost around $18.99 to $21.99 
Good Luck on your new adventure into "DIY building gaming PC's"   

TC