It looks like it can't find the package python-software-properties.
Could you try this: replace /etc/apt/sources.list (after backing it
up) with the following
deb http://security.ubuntu.com/ubuntu lucid-security main restricted
deb http://security.ubuntu.com/ubuntu lucid-security multiverse
deb http://security.ubuntu.com/ubuntu lucid-security universe
deb http://us.archive.ubuntu.com/ubuntu/ lucid main restricted
deb http://us.archive.ubuntu.com/ubuntu/ lucid multiverse
deb http://us.archive.ubuntu.com/ubuntu/ lucid universe
deb http://us.archive.ubuntu.com/ubuntu/ lucid-updates main restricted
deb http://us.archive.ubuntu.com/ubuntu/ lucid-updates multiverse
deb http://us.archive.ubuntu.com/ubuntu/ lucid-updates universe
deb-src http://security.ubuntu.com/ubuntu lucid-security main restricted
deb-src http://security.ubuntu.com/ubuntu lucid-security multiverse
deb-src http://security.ubuntu.com/ubuntu lucid-security universe
deb-src http://us.archive.ubuntu.com/ubuntu/ lucid main restricted
deb-src http://us.archive.ubuntu.com/ubuntu/ lucid multiverse
deb-src http://us.archive.ubuntu.com/ubuntu/ lucid universe
deb-src http://us.archive.ubuntu.com/ubuntu/ lucid-updates main restricted
deb-src http://us.archive.ubuntu.com/ubuntu/ lucid-updates multiverse
deb-src http://us.archive.ubuntu.com/ubuntu/ lucid-updates universe
This is the stock Ubuntu 10.04 32-bit/64-bit sources.
After you replace /etc/apt/sources.list with the above, do an
sudo apt-get update
then
sudo apt-get install python-software-properties
and let us know the result.
Regards,... Fred