Various documentation that I read said that the root of Ubuntu needed less than 200Mb. However, I've found that not to be true. In my situation, I ran out of disk space. So I've bumped the root partition to 500Mb. On my 80Gb drive, Here are my partition sizes:
medined@thog:~$ df Filesystem 1K-blocks Used Available Use% Mounted on /dev/hda1 481764 282766 173296 63% / /dev/hda8 51675672 923812 48126844 2% /data /dev/hda5 3099260 1593760 1348068 55% /usr /dev/hda7 10317828 556548 9237164 6% /usr/local /dev/hda6 10317828 337728 9455984 4% /var
I also have a 1,000Gb swap - mainly because when I tried to install Oracle it asked for a 750Mb swap file.
UPDATE: One mistake (there are probably others) that I made was that the /tmp path needs a lot of room because that is where installation place files. So two choices - either give the root partition another couple of gigabytes just for software installation. Or give /tmp its own 2Gb partition. Or, as I am doing, constantly tell each installation process to place temp files in a /data/tmp (or whatever) directory.