Windows Services Changes
Click on Start, Run and type MSCONFIG and press Enter again.
This will reopen the System Configuration Utility.
Click on the Services tab, then click on the option at the bottom called "Hide All Microsoft Services" to see what unnecessary Windows services are running that can be removed.

Disk Cleanup, Scandisk, and Defrag
Open My Computer
Right-click on the hard drive usually Drive C
Click on the Tools tab
Under Error Checking, click on Check Now. Optionally, you may want to check the boxes to "Automatically Fix File Errors" and "Scan For and Attempt Recovery for Bad Sectors"
Next, click on the General tab and click on Disk Cleanup. After the computer calculates the amount of files to remove, place a checkmark next to the type of files you wish to remove and click Ok. Read the descriptions for each type of file to determine if you should delete it.
Finally, click on the Tools tab again and under Defragmentation click Defragment Now
Click on the hard drive you wish to defrag, click on Analyze and then click on Defragment. This process may take some time to complete.

Changes to Windows Settings

Click on Start, Run and type MSCONFIG and press Enter. Click on the STARTUP tab in the System Configuration Utility to view all the items that begin on Startup. Each item on the Startup tab that is checked loads immediately after Windows starts. If there are lots of items here, this will slow down the boot time for Windows considerably. Each of these items can be toggled on or off simply by using the checkmark box to the left of the item. When you are done modifying the checkmarks to the Startup tab, click OK and you'll be asked to reboot the system.