New gaming rig help please!

awing

Honorable
Jan 15, 2013
5
0
10,510
Ok my budget is $600 i already have a monitor, a keyboard, a mouse, speakers, and a graphics card (EVGA GTX 550ti). I play mostly WoW, League of Legends, Diablo 3, and I hope to be able to play guild wars 2 on settings that don't look like complete crap. Any and all help is appreciated.
 

awing

Honorable
Jan 15, 2013
5
0
10,510
For people that want all the info.

Approximate Purchase Date: In about a month

Budget Range: $600

System Usage: Gaming, watching livestreams

Monitor: Already have one

I need an OS

Preferred Website(s) for Parts: the cheapest

Location: South Carolina USA

Parts Preferences: Intel

Overclocking: No

SLI or Crossfire: No

Monitor Resolution: 1024x768
 

awing

Honorable
Jan 15, 2013
5
0
10,510
How much of a better card?
And also my computer is running an intel cleron 450 2.2 ghz single core processor which bottlenecks my GPU, but I get 60 fps give or take a few in WoW just questing, when other people come into play is when i start lagging.
 
PCPartPicker part list / Price breakdown by merchant / Benchmarks

CPU: Intel Core i5-3470 3.2GHz Quad-Core Processor ($179.99 @ NCIX US)
Motherboard: ASRock H77 Pro4/MVP ATX LGA1155 Motherboard ($87.55 @ Newegg)
Memory: Mushkin Blackline 8GB (2 x 4GB) DDR3-1600 Memory ($35.57 @ NCIX US)
Storage: Seagate Barracuda 1TB 3.5" 7200RPM Internal Hard Drive ($64.99 @ NCIX US)
Case: Cooler Master HAF 912 ATX Mid Tower Case ($51.52 @ NCIX US)
Power Supply: Corsair Builder 500W 80 PLUS Bronze Certified ATX12V Power Supply ($49.99 @ Amazon)
Optical Drive: Samsung SH-224BB/RSBS DVD/CD Writer ($20.58 @ Amazon)
Operating System: Microsoft Windows 7 Home Premium SP1 (OEM) (64-bit) ($89.98 @ Outlet PC)
Total: $580.17
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2013-01-15 22:21 EST-0500)

This is something to think about. It will be very good. Your GPU will hold you back the most until you upgrade it. You should still get medium settings in modern games though.