Moving a Message with a Keystroke in Apple Mail

I've been using Eudora e-mail for more years than I care to admit, but I finally switched over to Apple Mail (v3.3 on 10.5). I have to say, Apple Mail is very good. However, there's one annoying thing I can't figure out.

How do you setup Apple Mail to move a message from the Inbox into a specific folder with a single keystroke or single button click?

It's possible to drag-and-drop a message into a folder, but that gets very tedious (and will lead to carpel tunnel pain), especially if you are going through dozens of messages. Sometimes after reading a message I simply delete it, but usually I want to move it into my "Done" folder in case I need to access the message again. Repetitive drag-and-drop to move each message into my "Done" folder is killing my wrist. A keystroke or button to move a message into my "Done" folder would be great.

I tried to use Keyboard Shortcuts in System Preferences, but it doesn't seem possible. I looked at AppleScript, but I couldn't figure out how to trigger the script. I don't mind writing a script, but I prefer not to download 3rd party software for such a small task.