To keep it simple, I do the following. I'm using Excel 2000, so it might be different for other versions.
At the beginning of your sub, put:
Dim objOL As New Outlook.Application
Dim objMail As MailItem
Set objOL = New Outlook.Application
Set objMail = objOL.CreateItem(olMailItem)
Then to actually send the workbook, use:
ActiveWorkbook.SendMail "My Distrubution List", "My Subject", "false"
Then at the end of your sub, put:
Set objMail = Nothing
Set objOL = Nothing