Change your antivirus program to Avast or Microsoft Security Essentials (If you have Norton or McAfee you will need to download their uninstaller to remove completely)
Uninstall programs you do not use
Use msconfig Start Tab and uncheck all except antivirus program and Microsoft, Apply and restart the machine
Do not keep too many windows or browser tabs open at the same time
Make sure that your hard drive has at least 15% free space, delete files if not. Use an external drive if needed.
Avoid many online games that specifically run slow
If this does not make it fast enough, get a laptop or a desktop.
You have to be a little bit crazy to keep you from going insane.