The assigned device would probably be a function of which usb/firewire port is connected and the order you connect them.
It may be better to use something other than the device to mount it, such as the label or the UUID number.
You can use the udevinfo program to get information about the device. The information will include the label, if there is one and the UUID number of the device.
Code:
udevinfo -q env -n /dev/sdb1
Now use cut and paste, to replace the device field in /etc/fstab with "UUID=<paste uuid number here>"
In a recent message I posted an actual example from my laptop:
http://www.linuxquestions.org/questi...14#post2734314
It is in message #6.
This example is for an externel firewire drive formatted using the EXT3 filesystem.
I used the "user" and "noauto" options. This allows me to mount the drive without using sudo: "mount /media/lbigdisk"
My system (SuSE 10.2) uses udev and hal to automount devices. The hal helper program respects the /etc/fstab entry. Hopefully yours will do the same.
You might want to make a backup of /etc/fstab before and after the edit. I guess some systems dynamically edit the /etc/fstab file. I don't know about Ubuntu.