This is one of my favourite "Must have" Tools.
It's able to completely replace the Windows "Open with" Dialog in the Context Menu of all files.
(You can also have both entries if you need the Windows "Open with" sometimes.)
With "OpenExpert" you can rightclick a file and create a list of suitable applications for the filetype.
Now you can choose between several Applications you want this filetype to be opened with.
You can also specify an application for all filetypes (i.e. notepad).
You can create a list of suitable Applications with DOpus too, but not in such a comfortable manner.
Should be a feature natively integrated in DOpus I think!
You'll find a detailed description and a screenshot here:
http://www.baxbex.com/openexpert.html
There is also a german site:
http://www.baxbex.de/default.htm
To have the OpenExpert Context Menu entry in the customized Context Menu of DOpus go to "Settings=>File Types" and doubleclick "All Files".
Now go to the "Context Menu" Tab. Create a new entry by clicking "New..." and give the entry the name "Open with...".
For the Function you need the GUID of OpenExpert. You'll not find the GUID at the Standard places of Windows registry!
I had to search the registry for "OpenExpert" to find it.
For me the entry for "Function" is (should always work):
FileType ContextForce ContextMenu={67C63340-679B-11D2-92EE-000021474C11}