Second Hard Drive

Have XP installed on a small HD,C:, and a CD-RW,D:. Installed a second HD with XP for space. However, it is now E: with my ROM still being D:. When I boot up I can choose C: or E:.When I boot up in C: I can “see” E: in My Computer or Windows Explorer. Problem is when I boot up in E: there is no C: listed. Any help