If you have the rest of the drive free I would just go to the live Cd and fire up gparted. You can make the partition the size of the drive. It will take a while, don't hold your breath.
You do not want this to go fast. Everything must be right. Gparted has never screwed me yet. Backing every thing up is still a very good idea.
The reason you need the live CD is you do not want the drive mounted when doing this. If you could get Gparted to do it from your install (never tried it, it might do it) you would probably really screw something (your OS) very royally. If you have an install on another HDD you can do it from there (this is what I do).
The problem is that you are probably installed on one partition. This works. Two are a whole lot better. One for / and one for /home. This of coarse gives you three partitions counting /swap.
If I were you, I would look up the directions for making a separate partition for home. I have done it, it is a pain, it works really well and every thing works fine afterwards. The directions are in the Ubuntu Community Documentation some where. Ah found it;
https://help.ubuntu.com/community/Pa...ng/Home/Moving
You will have to expand your current partition to have room to work. You will have to have the new /home created to coppy that work to. Take your time, read the directions. All commands are copy/paste so it is pretty easy.
My first install was on one partition (Ubuntu 8.04.1 LTS). I left it that way until a few months ago when I switched to Debian. Wanted all my files intact and so had to do it. I had done it before with a copy of the same OS (Gparted is a handy bugger just copy/paste the partition to another drive or open space on the same drive). You will have to edit your fstab file. This is all covered in the directions.
I do not know where your /swap is but I would move it to the end of your drive. Make your current partition double its size. Make another partition that is about the size of your current one (big enough for every thing in your /home folder).
Use the directions completely. If it all works then you can edit your fstab and see if it works when you reboot. If so you can delete the /home folder you are now using (it having been copied to your new /home partition).
Shrink your / partition to a reasonable size. Most say 10 to 15Gb. I like to install things and keep my cached packages. Right now I am using 21Gb of a 30Gb / partition. Should have gone for 35 or 40Gb.
Expand your new /home to fill the space between / and /swap.
This will give you a more robust, flexible installation, make upgrades actually work better and you could switch from Ubuntu to any Debian based OS by simply installing it on your / partition and leaving /home unformatted by the installation (thus I am now running Debian Squeeze on my old 8.04 install). I would assume this would work going to RH branch OS' too but I have never done it myself (there is no reason I can see that it would not work).
To leave your drive as flexible as possible you could also delete the current /swap and after making your current partition big enough to hold double you /home folder, create, on the rest of the drive one "extended" partition. This is a type of "primary" partition but you can create many "logical" partitions within it. You are limited by the DOS convention on partitions to 4 primaries. I have 7 partitions on this drive counting /swap.
If you do not think you will ever want another install on that drive the 3 primaries will be no problem at all.
It is a lot easier to just install the bugger on 2 partitions. Why the installers are not configured to recommend and do this is beyond me. Some folks like a lot more than just / and /home. /boot is popular, /var is too. Next time you run the installer use the manual option (Ubuntu, to confuse things, now calls it, very clear and concise, "something else"). You will see all the options in the mount points menu for partitions.
I think most people with experience all use the manual partitioning option and most create the partitions before hand with gparted or some other tool before installation begins so that they do not have to trust the installer to make them. Just point it at premade/formatted partitions and not let it format anything.
You may want to check your messages here.
