NEED HELP WITH COMPUTER SPECS

Aight, so I am looking to buy a new PC when I came across this deal for 350$:

Computer Specifications:

• AMD FX 4100 BULLDOZER QUAD CORE 3.6GHZ (TURBO 4.2GHZ) WITH 12MB TOTAL CACHE
( Upgrade to a 6 Cores processor for only $75 more )
• GIGABYTE AM3+ MOTHERBOARD ( SUPPORT UP TO A 8 CORE FX PROCESSOR)
• 4GB DDR3 HIGH PERFORMANCE MEMORY
(Upgrade to 8GB DDR3 for only $50 more)
• ATI HD3000 GRAPHICS WITH HD READY AND TOTAL 2GB MEMORY WITH 512MB DEDICATED WITH VGA AND DVI PORTS
DUAL MONITOR SUPPORT READY FOR MORE SCREEN ROOM
(Upgrade to 1GB GDDR5 video card to play all the latest games like Diablo 3 MW3 or BF3 and more on HIGH to Ultra settings for only $125 More)
• 500GB SATA HARD DRIVE 72000RPM (Uprade to 1TB of HD for only $25 and 2TB is only $50 )
• 24X DVD BURNER DRIVE
• GAMING CASE WITH 250MM BLUE LED FAN ON SIDE PANEL TO MAXIMIZE COOLING
• 500WATTS POWER SUPPLY
• FAST ETHERNET PORTS (Upgrade to Wifi for only $25 more)
• OS: Windows 7 Ultimate 64bit
• Office 2007 & Nero 7 Ultra

And I am a rookie when it comes to computer knowledge so I was wondering what I should upgrade if I wish to use this computer for gaming like WoW, Diablo, Minecraft, etc. And also for making videos. Help is appreciated! P.S. I don't want to spend too much so basically, the basics and necessities I need to upgrade to run the games on Max Settings. Thank you