Something like this:
 Code:
$sData="2009/06/03 12:28:17  * FILENAME1.zip-1523KB * FILENAME2.zip-1435KB * FILENAME3.zip-1325KB * FILENAME4.zip-1229
KB * FILENAME5.zip-1379KB * FILENAME6.zip-829KB * FILENAME7.zip-1046KB * FILENAME8.zip-1137KB * FILENAME9.zip-1481KB * FILENAME10.zip-1554KB * FILENAME11.zip-1339KB"


$dTotal=0.0
For Each $sField in Split($sData)
	If InStr($sField,".zip-")
		$sFile=Split($sField,"-")[0]
		$dSize=CDbl(Left(Split($sField,"-")[1],-2))
		$sScale=Right(Split($sField,"-")[1],2)
		"File '"+$sFile+"' has size "+$dSize+" "+$sScale@CRLF
		
		; If the input contains a mix of KB, MB, GB then you will need to scale it
		; I'm scaling to the smallest unit (byte) so that no information is lost
		Select
		Case $sScale="KB"
			$dTotal=$dTotal+$dSize*1024
		Case $sScale="MB"
			$dTotal=$dTotal+$dSize*1024*1024
		Case $sScale="GB"
			$dTotal=$dTotal+$dSize*1024*1024*1024
		Case $sScale="TB"
			$dTotal=$dTotal+$dSize*1024*1024*1024*1024
		EndSelect
			
	EndIf
Next

; Display total, converted to MB
"Total size="+FormatNumber($dTotal/1024/1024,2)+" MB"+@CRLF


If you can guarantee that the numbers will always be KB then you can leave out the scaling, but it will work as-is.