I was testing just a basic XP PRO SP2 multiboot before adding all my apps and extra data & it work fine!
Then I went ahead and added everything (apps, extra winnt.sif settings) then I burnt the image (cdimage.exe -lAIODVD -bloader.bin -h -n -d -o -m \AIO-DVD E:\AIODVD.iso) using nero. Went to boot and got the following:
Error Booting from CD/DVD Drive
Press any key to reboot
All I changed (in terms of booting files) was adding extra lines into cdshell.ini for the extra winnt.sif settings.....