As I briefly mentioned in my post, I did try and install CD1 first, which was just the maps. I did get this installed, but what I had to do was copy the contents of the CD to my hard drive, then, using WinZip, extract the contents of the 5.2XX update over the top of the CD (i.e. new version of setup.exe etc.), this then allowed me to install it from what I recall. However, I then removed this when I realised I was using the wrong CD ... but it's possible it left something I missed to say the maps where installed. The second time round, I just installed the maps to my hard drive and copied across.