Hello Haru, If your computer is running slow here is some possible ways to repair it:
1.Defrag your drives.
2.Clean out your TEMP files.
3.Make some edits to your MSCONFIG
4.Download CCleaner <<<<Recommended.
First off, I want you to download a program called CCleaner. This will help you tremendously!
After you download this program, check all the processes and what not you want to be cleaned.
After you have finished doing this select the button labeled "Analyze" and wait for it to be analyzed. Once finished you may then select the button "Clean". You will be confronted with a pop up. Just confirm it and continue to clean.
After your computer has been cleaned by CCleaner you should see some fairly noticeable results. But we are not finished yet.
>>CCleaner will clean majority of the 4 things I listed above<<
Now we will defragment your drives. THIS WILL TAKE A EXCESSIVE AMOUNT OF TIME. I'd recommend doing this right before you go to bed and letting it run while you sleep.
To defrag your drive please click on Start>All Programs>Accessories>System Tools>Disk Defragmentor
Once you have selected Disk Defragmentor, select your C:/ to be defraged then choose either anaylze or defrag. Defraging it before analyzing it would be faster, but some people are paranoid and like to analyze everything beforehand.
Now wait a loonnng time for it to be completed.
After this you will want to edit your Start Up processes in your MSCONFIG. To do this click on "Start" and in the search bar provided type in "MSCONFIG" and press the "Enter" key.
Once done you will be prompted with a nice GUI consisting of a few tabs. Your going to need to select your Start Up tab.
Once in this tab please un-check all the unneeded start up processes. Note to make sure to leave all processes dealing with System32 checked. That is vital.
After you have completed all of the above reboot your computer and enjoy.