Close Adobe Acrobat from Excel - attn: NickHK

Does anyone know how to get a reference to Adobe and/or close the app?
I am using Windows XP with Office 2003 and Adobe Professional 6.

FYI, the following function starts Adobe, prints a file, and closes the
file. Now I want to close the app:

Public Function PDFPrintFile(argAdobeAppFullName As String,
argPDFFileToPrintFullName As String)
'START ADOBE APPLICATION AND PRINT A FILE
Shell argAdobeAppFullName & " /p /h " & argPDFFileToPrintFullName
End Function

Even if I use a return value with Shell, and try something like:

retVal.Quit

I get an error. Can anyone help? Thanks in advance.