That's not a simple procedure unless you simply use the restore disks and have it wipe and re-install the system.
Uninstall all programs you installed, go though your use files and use a file shredder like this http://download.cnet.com/Free-File-Shredder/3000-2144_4-75978088.html on them. Run the disk cleanup wizard and have it select everything and run it. Delete all history and files from the web browser.
That's not a simple procedure unless you simply use the restore disks and have it wipe and re-install the system.
Uninstall all programs you installed, go though your use files and use a file shredder like this http://download.cnet.com/Free-File-Shredder/3000-2144_4-75978088.html on them. Run the disk cleanup wizard and have it select everything and run it. Delete all history and files from the web browser.