checo,

If the only change you did is to make a new key and then delete the key, then No, your registry will not be damaged.  If you want to have the home page locked in IE then several programs will help you with this (and monitor for any changes done by malware).  SUPERAntiSpyware is a program that will lock the Home Page and check for any changes that malware tries to make to your browser.  You can download the free version from here; the free version does not interfere with Norton's scanning engines.