How to speed up PC?

Hi, i downloaded Windows 7 xDark 3.7(Base of Windows 7 Ultimate) and it's pretty good... I disable some service with xDark service tweaker by making the settings advance... I disable the selected box in Windows Feature(just those things i don't use at all...) I uninstalled those software i don't use that xDark installed... FireFox as it Add-On(which is pretty good) from xDark but I dont know it slows or not but i see the different(faster) I did other tweaks too but i dont see the Speed in the Computer... my computer is an E-Machine W5243 and it transfer file at 20-27MB/s(HDD 7200 RPM)... My bro has a really fast computer(build his own) and it transfer file at 40-60MB/s...(Not the HDD i know) I disable pretty much things/tweaks and it transfer file so slow...(regular with tweaks and stuff is at 18MB-22MB/s)... How do i make it transfer faster or by using CPU usages to 100% instead of it being at 10-30% and i cant even open FireFox even IE or Google Chrome... Any Ways that can speed up my computer by a little or a lot? E-Machine W5243...


BTW i dont know where to put this so i put it on Operation System because it's basically about Operation Speeds... So don't get mad/complaints...(Administrator)