Sorry but I don't (other than to use the same driver and see what happens if W8.1 doesn't install one).
I had a very interesting thing happen to me when I experimented installing W8 on a Dell Dimension 4700 with a Pentium 4 650 processor a couple of weeks ago.
W8 worked perfectly.
I upgraded to W8.1 and it failed telling me the processor was not supported.
So, there must be some hardware requirement changes (at least regarding the type of processor) between W8 and W8.1 that I was not aware of.