I find that it's not hard to disable a key. Here's how to do it:
1. Download MapKeyboard from download.com (27KB only)
2. Uncompress it, then open the MapKeyboard.exe (not installation is required)
A virtual key board will show up.
3. Click on the key that you want to disable. For my case, I click on RAlt to disable right Alt key.
4. Then at "Remap selected key to:", select "Disabled".
5. Finally, click "Save layout" and reboot the PC
If you failed to start the program, you will need to install Microsoft .Net Framework 2.0.
I think this can be useful, especially for some gamers who would like to disable the Windows key for you-know-what reason.
Besides disabling a certain key, the program can map keys as well.
Hope you find it useful too.