Sprogget, you cannot simply just change the system drive letter I'm afraid.
A usb drive? Sure. The system drive, no. The article you reference refers to non-critical drives. As you can see from this article, it's a little more involved when it's the system drive and is very likely to result in a 1-way ticket to blue-screen central:
Change System Drive Letter in Windows XP
The whole concept of drive letters is actually ridiculous and a flaw almost exclusive to Microsoft. Proper operating systems are not bound by this idiocy.