Ok well I have a Compaq Persario F500 (F579). I just recently downgraded from Windows Vista to Windows XP Professional. Now my battery dies in less than 30 minutes. I have tried calling Compaq Tech Support but they said that because I downgraded my OS that my warranty was null and void and in order to receive support I must reinstall Vista. Right now that is not an option, however it will be in the near future. This is really irritating. Has anyone else had this problem? Anyone know a solution? Any tips would be greatly appreciated.