If you use the command(s):
dmesg | grep sr
grep will search through dmesg for scsi cd devices /dev/sr0, /dev/sr1, etc. on your system, from this you should be able to figure out which device is your DVD and which is your cdrw, from what you say your DVD should be 'sr0', and your cdrw 'sr1' (dmesg will just say sr0 or sr1, when in actually the devices are /dev/sr0 and /dev/sr1)

Then if you do a:
ls -al /dev/sr*
you will see that /dev/sr0 is linked to /dev/scd0 and /dev/sr1 is linked to /dev/scd1, (enough technical stuff).

What I usually do (logged in in as root) is create a cdrw device that I use instead of having to remember if my cdrw is device /dev/sr0 or /dev/sr1 etc. I do this: (assuming your cdrw is /dev/sr1)
ln -s /dev/scd1 /dev/cdrw
I also make a mountpoint /cdrw (still as root: mkdir /cdrw), then edit /etc/fstab and copy the /dev/cdrom line and change /dev/cdrom to /dev/cdrw and the mountpoint /cdrom to /cdrw, save the /etc/fstab file and then I can mount my cdrw. If you want a KDE desktop icon for your cdrw right click on the desktop and select "Create New" then "CdRom Device", name it select the "Device" tab and from the dropdown select: /dev/cdrw (/cdrw).

HTH

rock