Best to always take a look at the registry in the system before running any reg file to get a handle on what it is going to change.
In this case one would check out HKEY_CLASSES_ROOT\.mdb and see what it is already pointing to. In my XP Pro install of 2007 it points to Access.MDBFile
This key is HKEY_CLASSES_ROOT\Access.MDBFile
Add the commands for mdb context menu there.
Similarly the accdb key.
The script published at the link repoints .mdb to Access.Application.8
Then it adds the keys there. However this is a whole new key unless you have Access Version 8 (which is I expect is pre A2000).
Consequently since the reg file does not include the Open command for Access.Application.8 the Open command is no longer available for mdb files. One of the new keys would become the default action on a double click.
I do wonder how many people have used that reg file and remain suspicious of Devavish to this day. They probably never again touched their registry again.
BTW If you have used the old script and it broke your system just edit HKEY_CLASSES_ROOT\.mdb entry back to Access.MDBFile and delete the Access.Application.8 key.
Actually I never thought about it until I saw this thread and thought that it would be handy sometimes, particularly the Compact command.
We have several old badly designed databases lingering on our network that I haven't had the chance to rework yet. Several of them get copied each year and old records removed. It originally took me quite a while to get compact them all by opening them and using the compact command internally.
The context menu is great. Couple of clicks and they can be compacted much more quickly then opening them.
I have always been a fan of context menus and been managing them in the registry since Windows 95. I first got into it when some programs I tried out left stuff behind when uninstalled.