It would be a good idea to accumulate drivers for the mediator here. Despite owning two mediator boards, the drivers and their updates are the biggest PITA when dealing with Elbox.
I've just pushed an update to the guide which lists which versions of the drivers are in which of the updates. As I mentioned a couple of posts up, you definitely don't need to install any intermediate versions, just the latest MMCD (2.0) and then the latest MM_CD_UP (2.5 at the time of writing)... (plus any individual files that have been updated, like the pci.library v11 that was released last month).
Please let me know if you have any MMCD or MM_CD_UP versions that aren't listed in the guide (and send me a copy so I can add them!)
I went straight to the latest mediator install and then the latest multimedia installer with no problem after a clean install on my A4000T. I've also done it for a friends machine. The MM-up! disk that comes with them is out of date from the start and no point in using it.
Yeah I was a bit disappointed that the CD didn't have any obvious version number on it, and was out of date, but installing MMCD 2.0 and then MM_CD_UP 2.5 has worked fine for me, and isn't too much work

I also think their install is a giant mess of ugliness, especially the AHI stuff, it seems to end up shoving a smear of different versions onto your hard disk.