Easy way to go to Appearance Tab of your Display properties in Vista
just by creating shortcut on your desktop.

1st) Right click your desktop then scroll to New > Shortcut

A window will appear; just type in the location bar;

control desk.cpl,,2

then click next and then type a shortcut name in it;
you can type any name you want; or just name it Appearance..

Thats it you can click the shortcut you’ve created and it opens the appearance tab,
and choose the theme u installed..

You can also use this in the location bar;

Desktop Icon Settings = control desk.cpl,,0
Screensaver Settings Tab = control desk.cpl,,1

Hope it will help you. Thanks!