I've just been playing around in Word and have discovered a few things. For any character in Word, if you place the cursor to the right of the symbol and press ALT+X, the symbol is replaced by its Unicode value in hexadecimal. The reverse is also true. If you type the hexadecimal Unicode, place the cursor to the right of the code, and press ALT+X, the code value changes into the symbol.
There appears to be something in Word that converts the 900-series decimal values to hexadecimal. As stated before, when I press and hold ALT while typing 945 I get a lower case alpha. However, when I place the cursor to the right of the alpha and press ALT+X, the symbol changes to 03B1 - the hexadecimal form of 945. When I press ALT-X again it changes back to the alpha symbol. However, when I type 945, place the cursor to the right and press ALT-X, I get the symbol whose hexadecimal value is 945.
I think the reason my Word at home doesn't work is because of the older version, though I'm going to experiment with it further. I'm interested to see if I can get Greek symbols to work using the ALT+X method with the hexadecimal Unicodes.