re-installing Windows XP Pro

Since repair of a faulty XP Pro installation has never worked for me is it possible to re-install XP over an existing installation as I can do with Windows ME, for example, so everything from other programs/setup stays there. I have re-installed Me on another computer and then continued on using the computer withou any further problems. Whenever I have re-installed XP Pro I have deleted the directory/partition where it was installed and installed a fresh copy over the previous installation. The reason I ask is that I have computer with XP Pro which is not functioning properly[very slow to boot up and close down; occasionaly works at normal speed]and I would like to re-install XP so all the other programs data/setup remains and can be used after installation of XP Pro.