A. You can use either for NT. REGEDIT does have a few limitations, the largest is that it does not support the full regedit data types such as REG_MULTI_SZ, so if you edit this type of data with REGEDIT it will change its type.

REGEDIT.EXE is based on the Windows95 version and has features that REGEDT32.EXE lacks (such as search). In general REGEDIT.EXE is nicer to work with. REGEDIT.EXE also shows your current position in the registry at the bottom of the window.

REGEDT32.EXE allows full ACL modification on all registry values which REGEDIT.EXE does not.

It is possible to mount an additional hive with REGEDT32 and then search it with REGEDIT. You can only do this when you use them in tandem (thanks to Steven Yarnot for this tip)

1. Launch REGEDIT32
2. Go to the HKEY_USERS window
3. Highlight the root key (HKEY_USERS)
4. Select Registry | Load Hive
5. Browse to the profile of another user on this pc, select the NTUSER.DAT file in their profile folder (\WINNT\PROFILES\USERNAME) Give this hive an easy name like "TargetUser"
6. Notice that under the HKEY_USERS key that "TargetUser" has been added as a subkey.
7. Launch REGEDIT (do not close REGEDT32)
8. Notice that under HKEY_USERS, there is a TargetUser Key......

You can use REGEDIT to search this subkey.

Further, you can use this feature to export settings from one registry hive to another. 

9. Export a subkey of the Key TargetUser Using REGEDIT (until you are comfortable with this, I recommend a small, harmless key....)
10. Close REGEDIT
11. Highlight the TargetUser Hive in REGEDT32
12. Select Registry | Unload Hive
13. Repeat steps 2-5 on another user profile. (Use the same name for the key)
14. Double-click the .REG file you exported; the items you exported from the first user will now be imported to the second user!

When you are done, do not forget to properly close up shop, only one user can mount a registry hive at a time:

15. Highlight the TargetUser Hive in REGEDT32
16. Select Registry | Unload Hive


The information in this FAQ relates to Windows 2000 and Windows NT. For Windows XP, Microsoft has merged the functionality I've described into REGEDIT.EXE