excel batch macro?????????

OK, I have about 900 excel files (and more to come). In each file I have to fill an entire column with a certain formula. In one file It’s easy. Just fill in one cell and drag over the entire column. But what about hundreds of files?
Is it possible to add the formula to all these files at once with something like a batch macro?
Can anyone tell me how this can be done, or where I can find the proper information?????

Thanks!

you could create a macro that would copy a set amount of data/formula into any number of cells then copy the macro across sheets, which would be tedius. If you want to do it all in one blow then you are crossing the line into scripting (VB macros) or a stand alone type script (maybe perl?) sadly Im not much help there, only things I did were by trial and much error, and were not on that sort of scale. Sorry maybe try asking in the programming forum? Shouldnt be a too difficult task for someone who knows thier stuff.

Excel is a big nightmare for me!!!!!!!!!!!!!!!!