It's working, praise the gods.

I'm using someone's (possibly hoom?) edu-switching programme, so that's made switching from custom to campaign a lot easier.

Oddly enough, as I went to install 1.0 it came up with the modify/repair/uninstall screen, even though it should already have been gone.
So I un-installed 1.0 using that, and found there were traces of BI left on my pc (even though any folder containing that should be gone also).

I also somehow managed to delete my newly installed vanilla Rome while un-installing BI, but by that point I couldn't be bothered deleting my prepped folder and re-installing everything again (in other words, I can only play EB, but hey, who wants to play anything else?)

Game looks great so far, just did a quick CB and a few campaign turns.

Thanks for all the help man.
Anyone who can, can feel free to close this thread now.