Local Disk (G:)

Cant you just change it like you would a portable drive as in...

i dont know if this will work, though i don't see why not.

start > right click on "My Computer" > then click on Manage > look for the menu item called "Disk Management" > then right click on your G: Drive > click on change drive letter and paths.. > then theres a drop down and you can call it what ever you want.

pics;

 Spoiler

Then

Unfortunately, that method does not work with system or boot drives.

The OP stated he has XP (which I am also running) and unless it's a new feature with Vista, you are unable to change the drive letter of a system or boot volume. There's essentially a flag the operating system affixes to those volumes that prevents the end-user from tampering with them. It'd be an easy way to screw everything up.