Windows only: Portable utility My Drive Icon easily sets custom icons for each of the drives in your My Computer panel—instead of an otherwise complicated registry hack.
Using the utility is simple enough—just choose an icon, use the Apply Changes button, and refresh your My Computer screen to see the new icon. You can rename the label at the same time, or you can even use the utility to reset the icon back to default—useful when dealing with a system where the manufacturer used some strange ugly icons in place of the defaults.
My Drive Icon is a free download, only works in Windows XP in our testing, but your mileage may vary. If it does work in Vista for you, let us know in the comments.