Dispatch('Excel.Application') on Vista from Task Scheduler

[Cupric]

I have a python script that runs fine from the command line or from
within IDLE, but doesn't work through the Vista Task Scheduler.

The script downloads some csv files and then uses pywin32 to combine
the csv files into a single document. When I run it through the task
scheduler, it downloads the csv files, but then doesn't seem to launch
excel. I can't figure out what is wrong or how to add enough logging
to tell.

I'm using Python 2.6 and pywin32-212.win32-py2.6 on Vista.

Code snippet below.

Any ideas? Does it have something to do with permissioning on Vista?
I'm running the task as my regular user (that has administrative
privileges).

Thanks,
Theo
---------------
from win32com.client import Dispatch
....
        excel = Dispatch('Excel.Application')
        excel.visible =0
        print 'launched excel'
        workbook =excel.Workbooks.Add()
        Sheets = workbook.sheets
        defaultWorksheets = workbook.Worksheets(1)
        excel.application.displayalerts = 0

        for port in portList:
            print 'about to open' + basePath + port.filename
            port_book = excel.Workbooks.Open( basePath +
port.filename)
            port_sheets = port_book.Sheets

            datasheet = port_sheets(1)

            datasheet.Activate()
            datasheet.Cells.Select()

            excel.Selection.Copy()

            Sheets.Add().Name = port.name
            newsheet=workbook.Worksheets(port.name)
            newsheet.Activate()
            newsheet.Paste()

            port_book.Close(SaveChanges=0)