Need to format your pc as it may contain virus
I agree with Jorge, Just follow Google guidelines an get high amount of traffic to your website, and your CTR should always be on lower side. Depends your Page Views and clicks.
Your pc is bit old having DDR2 type memory which supports up to 4 gb, the graphic card is pcie express 2.0 . Overall even if u upgrade all these parts there will be only 5- 10 % of performance difference. If you purchased a good graphic card then you need to have a good Certified smps. And Buy a Samsung DVD writer.
If you Consider buying a new pc then here is the config.
asrock z77 extreme4 Motherboard
Processor:- Inter Core i5 3rd Generation
Ram :- Gskill ripjaws 1833 MHZ or corsair Vengenance
HDD :- 2 TB Western Digital Cavier green
SMPS :- Seasonic x760 Gold certified fully modular
Cabinet :- NZXT Gamma
Graphic card :- Saffire vapourx Hd 7950 3gb