Look at the Workbook "Open Event" in the VBA helpfile.
This example will save with a file name that you enter and the current date:
<font face=Tahoma><SPAN style="color:#00007F">Private</SPAN> <SPAN style="color:#00007F">Sub</SPAN> Workbook_Open()
<SPAN style="color:#00007F">Dim</SPAN> NewName <SPAN style="color:#00007F">As</SPAN> <SPAN style="color:#00007F">String</SPAN>
NewName = InputBox("Please enter the new file name", "New File Name") & " - " & Format(Date, "dd-mm-yy")
<SPAN style="color:#007F00">' Do stuff here</SPAN>
ActiveWorkbook.SaveAs Filename:= _
"C:\Documents and Settings\All Users\Desktop\Temp\" & NewName & ".xls", FileFormat _
:=xlNormal, Password:="", WriteResPassword:="", ReadOnlyRecommended:= _
<SPAN style="color:#00007F">False</SPAN>, CreateBackup:=<SPAN style="color:#00007F">False</SPAN>
<SPAN style="color:#00007F">End</SPAN> <SPAN style="color:#00007F">Sub</SPAN></FONT>
HTH,
Smitty