Working with the Windows Registry

[teh_sAbEr]

Hi everybody. I'm trying to write a script that'll change desktop
wallpaper every time its run. Heres what I've gotten so far:

#random wallpaper changer!
import _winreg
from os import walk
from os.path import exists
from random import randint

#first grab a registry handle.
handle = _winreg.OpenKey(_winreg.HKEY_CURRENT_USER,'Control Panel
\Desktop',_winreg.KEY_SET_VALUE)

def GenerateListOfWallpapers():
    targetDir = 'C:\Documents and Settings\Enrico Jr\My Documents\Jr
\'s Wallpapers'
    fileNames = []
    filePaths = []
    if exists(targetDir):
        #proceed to make the list of files
        for x,y,z in walk(targetDir):
            for name in z:
                fileNames.append(name)
        for item in fileNames:
            filePaths.append(targetDir + '\\' + item)
        return filePaths

def RandomlySelectWallpaper(filePaths):
    index = randint(0,len(filePaths)-1)
    RandomlySelectedWallpaper = filePaths[index]
    return RandomlySelectedWallpaper #it should be a string...

#now to edit the wallpaper registry key
newWallpaper = RandomlySelectWallpaper(GenerateListOfWallpapers())
print "Registry Handle Created."
print "Random wallpaper selected."
_winreg.SetValueEx(handle,'ConvertedWallpaper',
0,_winreg.REG_SZ,newWallpaper)
print "New wallpaper value set."

The problem is, every time I run it, I get an "Access Denied" error
when it tries to execute
_winreg.SetValueEx(), even though i've opened the key with the
KEY_SET_VALUE mask like it said in the help docs. Could there be
another problem or a better way to do this?