What would be the best upgrade for my PC?

[Inspector Gadget]

Hi, as the title says, I would like to know what would be the single best upgrade to make to my PC perform better, particularly for fairly light gaming.

These are the specs at the moment as listed on Speccy.

CPU:
Intel Core 2 Duo E8500 @ 3.16GHz 33 °C
Wolfdale 45nm Technology

RAM:
4.00GB Dual-Channel DDR3 @ 531MHz (7-7-7-20)

Motherboard:
Hewlett-Packard 3048h (XU1 PROCESSOR)

Graphics:
1024MB NVIDIA GeForce 9800 GT (BFG Tech) 68 °C

Any help greatly appreciated. Thanks.

 

[N3rdR4ge]

graphics card hands down
depends on your power supply what card you would want