Help! Advice needed on upgrading

[Matt_2000_17]

Hi, I'm looking into upgrading my current setup and would like you're advice on what components I should upgrade and what I should upgrade to. I don't have a massive budget but ideally I'd like to keep it under £250. System would be used for gaming, mostly Sims 3 and Simcity but also some FPS and simulation. Here is my current setup:

Intel Core 2 Quad CPU Q6600 @2.4GHz
Asus P5Q SE Plus motherboard
4Gb Corsair Extreme2 DDR2
ATI Radeon 4870 Graphics
OCZ Agility 3 240GB SSD
Hitachi 500GB HDD
Corsair VX550 PSU

Any suggestions is greatly appreciated. Thanks in advance.

 

[stickmansam]

OC the CPU to like 3.6ghz, with a good cooler like 212 EVO it's quite possible
GPU upgrade to the 7870XT
Added some ram but you can just put that money to saving up for a new build

PCPartPicker part list / Price breakdown by merchant / Benchmarks

CPU Cooler: Cooler Master Hyper 212 EVO 82.9 CFM Sleeve Bearing CPU Cooler (£25.45 @ Scan.co.uk)
Memory: Crucial 4GB (2 x 2GB) DDR2-800 Memory (£44.59 @ Amazon UK)
Video Card: Club 3D Radeon HD 7870 XT 2GB Video Card (£171.62 @ Amazon UK)
Total: £241.66
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2013-02-28 08:25 GMT+0000)

 

[Matt_2000_17]

My budget has increased and I've settled with the following spec

AMD FX-6300
Asrock 990FX Extreme3 motherboard
Sapphire HD7850 OC Edition 2GB
G-Skill 8GB (2x4GB) DDR3 1600Mhz RipjawsX Memory Kit CL9 (9-9-9-24) 1.5V
£400 inc. Delivery

Thoughts please?
Also would my current PSU be sufficient? It does have two 6 pin connectors.

Also thought about selling the old CPU, board, mem and GPU. How much do you think I could get for the lot?