As long as you're using windows not mac, this little wonder macro should do the actual inserting a picture bit.
Where I do CStr(CInt( that is just to make sure that we only have the number, and not any carriage returns / spaces / wacky table things around it.
Sub Replace_Number_With_File()
filenumber = CStr(CInt(Selection.Text))
FileName = "c:\temp\arrow" + filenumber + ".png"
Debug.Print FileName
Selection.InlineShapes.AddPicture FileName, False, True
End Sub
Then you need to iterate over the table, and find the right cells, and find each filename that you want to do, select the right bit, and then stick it in. If you know VBA, it is pretty doable, just a little fiddly, I don't have the time to play with it myself (it is much easier if you have the actual target document to hand anyway). If you don't know VBA, well at least the macro above will let you select a single number and replace it with a picture.
Joe