Jamie93 Asked: I bought this computer for ($350). Was it a good buy/can i sell it for more,will it run league of le

WOW superstore near my location was having a closing down sale and they were selling the computers that they were using, i bought one for $350 AU I was just wondering if it was a good deal or not. And if i chose to sell it could i make anymore? Any replies would be truly appreciated.
Here are the notes on the computer:

Operating System: Product key on the CPU, Windows 7 professional 64-bit (6.1 build 7600)
Manufacturer: Dell inc
Model: OptiPlex 990
Processor: Intel(R) Core(TM) i5-2400 CPU @ 3.10GHz (4 CPUs) 3.1ghz
Memory: 4096MB
DirectX Version: DirectX 11
Page file: 1429MB used, 6255MB available
GRAPHICS:
Name: Intel(R) HD Graphics
Manufacturer: Intel Corp.
Chip Type: HD Graphics Family
DAC Type: Internal
Approx. Total Memory: 1696MB

300GB of Hard Drive Space, Genuine Microsoft Software., Dell Pro Mouse and Keyboard included.
A Samsung 15 inch Screen Aswell.
just wondering if i made the right choice in buying it, and if i sold it what could i get for it.
i play alot of online games like League of Legends and RIFT, Would getting a 8gb ram/1tb of Hard Drive and a 3gb Graphics Card be a positive choice, aswell as a PRO Gaming Mouse and Keyboard.
All responses would be appreciated.

Thank-you for taking the time to read this.

Jamie