|1) Uninstall the programs that you don't need.|
2) Delete the files you don’t need (even if they are 250kb or less) – You can obtain highest disk performance when your hard drive space isn’t over 25% used.
More common sense
3) Use the disk clean-up option in Windows to regularly clean up the system junk files.
About the only useful suggestion
4) Turn off System Restore feature
Not always a good idea.
5) Use a reliable registry cleaner to clear the windows registry
The ain't no such thing. Steer clear of them, they are snake oil and cause more problems than they solve.
6) Regularly scan the computer for viruses and spyware
Anybody that has spent more than a day in front of a computer should do that as a matter of routine.