I can not change my XP theme.. Please Help..?

I liked a theme called leopad wile I was surfing net. After getting the zipped file I can't make it or keep it as my theme. I also liked some other themes but when I tried to download them I got Pdf file. And its not opening. How Can over come this problem?I can not change my XP theme.. Please Help..?
If u r really a computer geek, try to play with registry values



Change the following keys as per ur requirement



[HKEY_CURRENT_USER\Software\Microsoft\?br>
';NoDispBackgroundPage';=-

';NoSaveSettings';=-

';Wallpaper';=-

';WallpaperStyle';=-I can not change my XP theme.. Please Help..?
got to START %26gt; RUN type regedit

the change below setting as per the given sample... set it null .. it will help you ..





[HKEY_CURRENT_USER\Software\Microsoft\?br>
';NoDispBackgroundPage';=-

';NoSaveSettings';=-

';Wallpaper';=-

';WallpaperStyle';=-



[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft?br>
';NoDispBackgroundPage';=-

';NoSaveSettings';=-

';Wallpaper';=-

';WallpaperStyle';=-
maybe give a try to installation themes....the one who gave answer by using regedit also helps but if u miss a single part..your system would crash....you can also try tune up utilities 2009...select theme using tune up and click to apply it....