Note: this is assuming you're wanting to add and format a new drive -- don't follow the directions below if you're wanting to keep the data on that drive!
Have you initiated and formatted the drive?
If not, and since you're a GUI fan, not much out there can beat the functionality of Gparted.
go to your command-prompt and type:
Code:
sudo apt-get install gparted
once that's done and installed, type:
it should pop up a nice GUI for the program and you're in business. If you need to initiate the drive, it'll tell you, and then you can format to the correct filesystem (I'd recommend ext3 or reiserfs for Ubuntu 8.10 -- if you're going to use the drive for a lot of larger files, like movies, go for XFS instead).
The user interface is pretty self-explanatory, so you shouldn't have much trouble there.
From there all you have to do is mount it and/or set up your /etc/fstab -- there's a ton of information out there on how to do that, so I won't get into it here.
Hope that helps!