Excel OLE Problem

You can always go to the View|Object browser menu item, select the Excel library, select the sheet object and view what the available properties and methods are.  In this case I looked up Cells and saw that this is a method available to the Application object.  So, maybe you want to be doing CreateObject("Excel.Application")

MD

I wrote this just for you !
In Project | References set a reference to Microosft Excel Object Library.

    Dim XLApp As New Excel.Application
    Dim XLWS As Worksheet
    Dim XLWB As Workbook
    Dim XLCellRange As Range

    XLApp.Application.Visible = True
    Set XLWB = XLApp.Workbooks.Add()
    Set XLWS = XLWB.Worksheets.Add()
    XLWS.Name = "Worksheet Name"
    XLWS.Columns("A:A").ColumnWidth = 25
    XLWS.Columns("B:B").ColumnWidth = 15
   
    With XLWS.Cells(1, 1)
        .Value = "A cell value"
        .Font.Size = 14
        .Font.Bold = True
    End With

Error : Invalid use of new keyword!!!

Hey, everyone is just re-submitting (granted, a more detailed explanation of) my rejected answer!  Here's another thing you could try with your original code that might work.

change
ExcelSheet.Cells(1, 1).Value = "This is column A, row 1"

to
ExcelSheet.Application.Cells(1, 1).Value = "This is column A, row 1"

MD

Your line:
   Set ExcelSheet = CreateObject("Excel.Sheet")
will create WorkSheet in Excel 7, but WorkBook in Excel 8.

You can replace your line with this 2 lines:
   Set ExcelBook = CreateObject("Excel.Sheet") ' this will create XLbook
   Set ExcelSheet = ExcelBook.Sheets(1)

Your second line works:
   ExcelSheet.Application.Visible = True
because Workbook also has Application property

but your third line won't work (Workbook doesn't have Cells)