What most likely happened is that Ubuntu was working on/already resized your Windows partition (assuming you had one) and added one or two for itself. Most, if not all, Linux distros require root and home partitions where the system data and user data is kept, respectively.
If you still have Windows on there somewhere (if you were trying to dual boot) you should boot up into Windows and to the partition manager. Control Panel -> Computer Management -> Disk Management
In there you will be able to see your XP/Vista Installation and any other partitions that are on your computer. If you have Vista you will b e able to erase the partitions you don't want, and dynamically resize the Vista partition if you don't want to bother with Ubuntu anymore to take up the remaining space. If you have XP it's not quite as simple since XP can't dynamically resize itself. You can still erase the other partition and format it as NTFS though. You just won't be able to expand your main Windows partition to take up the remaining space like in Vista.
To expand the XP partition to take up the remaining space you can use Paragon Hard Disk Manager or Acronis Disk Director.All these are paid programs. In lieu of them, I would like to recommend something free and Linux based: Gparted. http://gparted.sourceforge.net/index.php
It's free and it does the same job. Just be patient with it and read the documentation.
To sum up: Ubuntu probably allocated that space and made the partitions. That's why your drive is smaller. To get back the space, delete the ext3 (most likely) partitions and voila! Also, most Linux distros install a swap space for you to. Called swap. Delete that if you're not using Linux as Windows has it's own thing.
If a Windows partition doesn't boot up and you want that back I would boot your computer with Gparted anyway, delete the ext3 (or whatever Linux partitions are there anyway) insert a Windows recovery disk and follow the instructions for a recovery/repair. This link gives you some directions: http://www.michaelstevenstech.com/XPrepairinstall.htm
If you actually want to try Ubuntu again without getting impatient then throw in the Ubuntu Live CD and go for it again! Just delete the partitions it made and go through those same steps. I recommend trying PCLinuxOS, just as user friendly as Ubuntu, KDE based, and without the gigantic corporation feel. There's also a gnome variant that is sexy as all heck! www.pclinuxos.com
And in the future, try not interrupting that process
Edited by psych1610, 24 August 2008 - 04:16 PM.