I understand perfectly what you are trying to do. You want a fully working backup of your game on one DVD rather than 4 CDs. You would like to make this single DVD from ISOs you extracted from those CDs.
You can extract all the iso’s and burn to a single DVD if you wish, but as I already stated, when you try to install the game, the instalation routine will fail.
Yes, there is a DVD version of the game, but the installation program, game executable and possibly more files will be different than the CD version.
In the DVD version you will not need to swap discs but in the CD version you do. The CD version installer knows to look for the next CD in the sequence, the exact layout of that CD and the files it should contain.
When it comes to the prompt for CD 2 the install routine will be looking for a disc with the exact layout of that CD. As your DVD will contain all four CDs the structure and layout of it will be very different to what the installer thinks is the right disc and the install process [B]will[/B] fail.
If you still want to try this I suggest you use a DVD+/-RW to save wasting a disc.
Open the ISOs in winrar and extract them to a folder on your hard disk.
Burn the files to the RW and try the install routine.
The chances are the installer will ask: “Please Insert Disc Two”. You will click ok as all the game files are on the disc. As they are not in the format the installer is looking for it will continue to ask for disc two.