Changing the Desktop theme programatically

I want to change the desktop theme through program. Can I? Can you help me with some idea?

Thanks in advance,
Mahesh

::SystemParametersInfo(SPI_SETDESKWALLPAPER, 0, "C:\\UNTITLED.BMP", SPIF_SENDCHANGE | SPIF_UPDATEINIFILE | SPIF_SENDWININICHANGE);

Thanx.

I have already looked into it. I can change the Wallpaper by using this. But whats about the desktop theme? I think, even i can't change the screen saver using this. (can only enable/disable and know whether it is enabled or not) I want to change the theme not only the walpaper.

Once again thanx for ur interest and reply.

Mahesh