Associating .5250 with my terminal emulation application in WinDoze XP is easy: just go to Folder Options/File Types, add a new extension, and associate it with:
"C:\Program Files\Java\jdk1.6.0_12\jre\bin\java.exe" -jar J:\emulator\jars\emulator.jar "%1"
But how do I do the equivalent in WinDoze 7?
I did a GOOGLE search and found something about "assoc" and "ftype" commands, but if I try these, from what is supposedly an admin account, I get "Access is denied."
(The more you overthink the plumbing, the easier it is to stop up the drain!)