Remapping Drive letters

My partitioned drive letters have changed following the reinstallatio of Windows 2000 (to resolve a registry problem). I now have D:\Winnt instead of G:\Winnt. G is now my CD-ROM drive, which has become disfunctional. I cannot now assess my program files which were on the G drive. How do I map the new D:\Winnt to the old G:\Winnt. My system is partitioned into Win 98 and Win 2000.