If you have a system install Live-CD,and you want to create an .iso image file from this CD.

Follow these steps:

1.Insert this CD into cd-rom.

2.You ubuntu will auto-mount this,and you can see an icon on desktop.Open up terminal(Applications->Accessories->Terminal) and type:

mount

You will see something like this:

/dev/sda7 on / type ext3 (rw,relatime,errors=remount-ro)
tmpfs on /lib/init/rw type tmpfs (rw,nosuid,mode=0755)
proc on /proc type proc (rw,noexec,nosuid,nodev)
sysfs on /sys type sysfs (rw,noexec,nosuid,nodev)
varrun on /var/run type tmpfs (rw,nosuid,mode=0755)
varlock on /var/lock type tmpfs (rw,noexec,nosuid,nodev,mode=1777)
udev on /dev type tmpfs (rw,mode=0755)
tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev)
devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=620)
fusectl on /sys/fs/fuse/connections type fusectl (rw)
lrm on /lib/modules/2.6.28-15-generic/volatile type tmpfs (rw,mode=755)
securityfs on /sys/kernel/security type securityfs (rw)
binfmt_misc on /proc/sys/fs/binfmt_misc type binfmt_misc (rw,noexec,nosuid,nodev)
gvfs-fuse-daemon on /home/wraith/.gvfs type fuse.gvfs-fuse-daemon (rw,nosuid,nodev,user=wraith)
/dev/sr0 on /media/DEEPIN LITE XP 5.10 type iso9660 (ro,nosuid,nodev,uhelper=hal,uid=1000,utf

Obviously,the line “/dev/sr0 on /media/DEEPIN LITE XP 5.10″ shows my Live-CD mounted from /dev/sr0.This is what we need in next command.
3.Use this command to create and save .iso file to home folder(/home/user_name/):

dd if=/dev/sr0 of=~/winXP.iso bs=1000000 count=512 &&sync

Here thie iso file named winXP.iso.
Tips:
you can also create an CD using .iso from your local system by:

dd if=~/winXP.iso of=/dev/sr0 bs=1000000 count=512 &&sync

you may first make the CD bootable by Gparted.