delete duplicate rows in excel

I have a spreadsheet with columns a through f. Column "C" is an invoice # and is listed multiple times, depending on the number of items billed on this invoice. I'm trying to delete all multiple copies of this invoice leaving only the first instance of each (the first entry has the total sale). I found a macro on this forum from a while back and it will delete my duplicate invoices if I insert my invoice # to Column "A", but it get's my other columns out of sync. I think this macro was written for a two column spreadsheet. Here is the Macro that almost works:
Sub DeleteDupes()
Dim Iloop As Integer
Dim Numrows As Integer

'Turn off warnings, etc.
Application.ScreenUpdating = False
Application.DisplayAlerts = False

Numrows = Range("A65536").End(xlUp).Row
Range("A1:B" & Numrows).Select
Selection.Sort Key1:=Range("A1"), Order1:=xlAscending, _
Key2:=Range("B1"), Order2:=xlAscending, Header:=xlYes, _
OrderCustom:=1, MatchCase:=False, Orientation:=xlTopToBottom
For Iloop = Numrows To 2 Step -1
If Cells(Iloop, "A") + Cells(Iloop, "B") = Cells(Iloop - 1, "A") + _
Cells(Iloop - 1, "B") Then
Rows(Iloop).Delete
End If
Next Iloop

'Turn on warnings, etc.
Application.DisplayAlerts = True
Application.ScreenUpdating = True
End Sub

I'm not familiar enough with Macroes to know how to adapt this. Any help would be greatly appreciated.
Marv

Hi lefty55,

If you have your invoice numbers in Col A the following code loops through from the bottom of the range upwards and if it finds the same invoice number it deletes the duplicate row(s) leaving only the first instance of the invoice number.

Code:

Dim Iloop As Integer Dim Numrows As Integer 'Turn off warnings, etc. Application.ScreenUpdating = False Application.DisplayAlerts = False Numrows = Range("A65536").End(xlUp).Row Range("A1:F" & Numrows).Select Selection.Sort Key1:=Range("A1"), Order1:=xlAscending, _ Key2:=Range("B1"), Order2:=xlAscending, Header:=xlYes, _ OrderCustom:=1, MatchCase:=False, Orientation:=xlTopToBottom For Iloop = Numrows To 2 Step -1   If Cells(Iloop, 1).Value = Cells(Iloop - 1, 1).Value Then      Rows(Iloop).Delete End If Next Iloop 'Turn on warnings, etc. Application.DisplayAlerts = True Application.ScreenUpdating = True End Sub

Hope this helps

Seamus