Check in/out Book

I need a macro (Excel 2007) that will upon a text entry into column B, will automatically insert the current date into column C then return the cursor to column A and then "Save" the wookbook. Then, if possible, I would like it to trigger it to enter the current date whenever any entry is keyed or scanned into column D and then again "Save" the wookbook if not, this function may have to be done manually. I will be using a USB keyboard wedge scanner to enter data in columns A & B & D. The scanner is already programmed to TAB to the next cell