welcome onboard.
you own an older version of trainz if you want to enjoy trainz at its full you should atleast own trainz 2010.but with ts 2006 it will also work.
"Device not ready" is a sign of a bad DVD, disk image, or even a bad DVD drive. You might want to replace your disks or redownload the program if this was a digital download, or replace your DVD drive.
John is correct. It sounds like a faulty DVD drive to me. Also, bear in mind that if it's a CD drive you have, unless you have the 5 disc version you will need to get a DVD drive.