Here is an example.

Take the following and save it as Acrobat.udf:
Code:
; Acrobat check UDF
Function udfAcrobat_Has_AR4()
	Dim $sKey,$sEntry
	$sKey="HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\Adobe Acrobat 4.0"
	$sEntry="UninstallString"
	$sKey
	$udfAcrobat_Has_AR4=(ReadValue($sKey,$sEntry)<>"")
	Exit 0
EndFunction
 
; Acrobat install UDF
Function udfAcrobat_Install_AR4()
	; Do install / uninstall
	;
	;
	If INSTALL_WAS_SUCCESSFUL
		$udfAcrobat_Install_AR4=0
	Else
		$udfAcrobat_Install_AR4=1
	EndIf
	Exit $udfAcrobat_Install_AR4
EndFunction


You can now load up the functions and call them individually in your main script:
Code:
; Load Acrobat functions.
CALL "\\SERVER\Kix\Acrobat7.udf"
; Acrobat install check.
If udfAcrobat_Has_AR4()
	; Do something
	"AR4 installed - no action necessary"+@CRLF
Else
	; AR4 not installed - must install.
	If udfAcrobat_Install_AR4()
		"Failed to install AR4!"+@CRLF
	Else
		"AR4 Installed ok."+@CRLF
	EndIf
EndIf