Open Excel file for reading with VBA without display

Not sure if you can open them invisibly in the current excel instance

You can open a new instance of excel though, hide it and then open the workbooks

Dim app as New Excel.Application
app.Visible = False 'Visible is False by default, so this isn't necessary
Dim book As Excel.Workbook
Set book = app.Workbooks.Add(fileName)
'
' Do what you have to do
'
book.Close SaveChanges:=False
app.Quit
Set app = Nothing

As others have posted, make sure you clean up after you are finished with any opened workbooks

If that suits your needs, I would simply use

Application.ScreenUpdating = False

with the added benefit of accelerating your code, instead of slowing it down by using a second instance of Excel.

To open a workbook as hidden in the existing instance of Excel, use following:

    Application.ScreenUpdating = False
    Workbooks.Open Filename:=FilePath, UpdateLinks:=True, ReadOnly:=True
    ActiveWindow.Visible = False
    ThisWorkbook.Activate
    Application.ScreenUpdating = True

Even though you've got your answer, for those that find this question, it is also possible to open an Excel spreadsheet as a JET data store. Borrowing the connection string from a project I've used it on, it will look kinda like this:

strExcelConn = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" & objFile.Path & ";Extended Properties=""Excel 8.0;HDR=Yes"""
strSQL = "SELECT * FROM [RegistrationList$] ORDER BY DateToRegister DESC"

Note that "RegistrationList" is the name of the tab in the workbook. There are a few tutorials floating around on the web with the particulars of what you can and can't do accessing a sheet this way.

Just thought I'd add. :)