P&D Question. Finding the Desktop on XP.

Hi,
I have an application that needs to install a temporary program on the desktop of the computer. For Win95/98 I could use $(WinPath)\Desktop for the install location but this doesn't work on WinXP/2K.
Is there something that will find the desktop on these?

Alternatively, Is there a way to determine the OS of the computer that's installing the programs?
I'm thinking that I could place the temporary program in the "All Users" desktop for WinXP/2K.

Thanks,
Al.