VBA file naming help

Hi,
Does anyone have a good macro, that can lookup .jpg file names listed in Column A and re-name them with file names listed in column B (.jpg files are in one folder and need to be re-named into another folder on my desk top) Column A has unique values but column B may contain duplicates. If duplicate in column B it doesnt matter which image in column A its related to. It just needs to get named once.

Column A Column B
outside.jpg -->> rename to 456335.jpg
pool.jpg -->> rename to 876445.jpg
sansas.jpg -->> rename to 455434.jpg

Something like

    With Activesheet

        Lastrow = .Cells(.Rows.Count, "A").End(xlUp).Row
        For i = 1 To Lastrow

            Name .Cells(i, "A").Value2 As .Cells(i, "B").Value2
        Next i
    End With