DEAR FRIENDS,
Whenever i try to decompress and install a "tar ball" or a "deb.", the KPackageKit comes up with a pop-up-->"you have no backend support".I have the Lucid Lynx installed, as a dual-boot with XP.Kindly help me out. Many thanks!
regards,
vyver.

It matters where in the process you get the error. Is it upon extraction or upon attempting to install?

*.deb files should not need to be decompressed before installation. They can normally be installed directly with gdebi or similar utilities in a Debian-based distro.

*.tar.gz files are normally sources and need to be compiled. You may need to download and install some of the utilites needed to compile from sources.

To install packages from source code (tar balls) on Ubuntu, you need at least the build-essential packages installed. You may need other packages as dependencies depending on what it is that you are trying to install.
The packages from the Ubuntu repos should always be your first choice for installing packages in Ubuntu.
For newer versions of packages, or for stuff that is not in the Ubuntu repos, there are a lot of ppa repos that many people use. These are user created repos that are unsupported by Ubuntu and Canonical, but many people use them. See this:
https://launchpad.net/ubuntu/+ppas

To frankbell,
Thanks for the response! I am sorry for creating a small mis-understanding in phrasing my query.The decompress was meant only for the "Tar balls".The Debs are getting installed ok on double-clicking. The error message is while trying to install.
regards,
vyver.

In my experience, *.tar.gz files are normally not installed with a package manager, but rather by compiling them from source at the command line. This is usually best done as root. Decompress the file (tar -xvzf [filename] is the command line I learned to use, but they can also be decompressed using a file manager.

Open a terminal, cd into the directory created by the decompression, and run the commands.

Normally, they are

There is normally a text README or INSTALL file that explains the process.

I have never used a package manager to install from sources. It could be that Ubuntu 10.04 lacks some of the gcc or other libraries needed to compile from sources. I think I recall having to install some of the gcc tools when I first started using Ubuntu, but that was a couple of years ago and I'm hazy.

I recommend trying to compile from sources at the command line and noting the error messages.

Good luck.