How to run well dolphin

[Edward Elric]

Hi guys!!, I read the post: ''minium specs'' and I have some questions.

With this Pc I can run some games with a good speed (70-80), but others with only 40%-60%
Operating System: Windows XP SP3
Processor/CPU: AMD Athlon™ II X2 245 Processor, 2913 MH
Video Card/GPU: NVIDIA GeForce GT 440 (1 Gb)
Memory/RAM: 3 GB

My question is if I have to buy something or change some configuration of the PC or dolphin

PD.: sorry if my english is not good I'm studying it