There is a file called boot.ini which gives option for dual boot etc, so your system thinks it has 2 copies of XP on it. Run the system recovery software again and be sure it picks C: as the destination for the install. When done if it still wants to go to D: edit boot.ini to make C: the first option or remove the D: option if you dont want ability to boot off of D: if your system ever gets messed up as a next available preloaded os.