configured /etc/sudoers file.
Whoa! cola, I don't think that's how sudo is intended to be used at all! You just disabled one of the most fundamental (if flawed) security features of a *nix operating system, the fact that an ordinary user cannot perform arbitrary (and possibly damaging) actions! Even if you are the only person who has physical access to your computer (a desktop chained to a desk inside a locked office with a 24 hour armed guard?), you should login and work as your ordinary user except when you need to perform administrative tasks on your computer, when you should su to root, or if possible, set things up so you can perform specific tasks via sudo.
I presume you figured out how to use visudo to modify the sudoers file.
A simple example: say you have a small LAN with several computers, one called "turing", and you have many people with login accounts, and two admins, Sam and Bill
# User privilege specification
root ALL=(ALL) ALL
Neccessarily, root is allowed to run any command on any machine on your LAN. Sam is allowed to use sudo to run "ps -ef" and see all the processes (an ordinary user should not be allowed to see sensitive system processes) on any machine in your LAN, while Bill is allowed to run mbmon to monitor the physical health of turing.
(When you have shell running on turing you should see something like
If not, you may need to reconfigure the machine you want to call "turing" to make sure the OS knows its name, and then you should be able to refer to it by that name in the /etc/sudoers in other computers in your LAN. I think.)
In this example, ordinary users can run ps but won't see all the output.
Sam can run ps and see all the output on any machine, but Bill cannot. Bill can run mbmon on turing but not on the other machines in your LAN, and Sam cannot run mbmon on any machine in your LAN. When Sam calls "ps -ef" he will be prompted for his own password, so he doesn't need to know the root password (in a real multiuser system, only one person should know the root password). And when Bill calls mbmon he is prompted for his own password, so he doesn't need to know the root password either.
Most likely you are running Linux on only one computer at home, but even so sudo can be very useful as a way to lessen the chance of making a serious goof while working in a root shell, by allowing your ordinary user to run routine administrative tasks without having to give the root password.
As several others referred to above, you can easily make a typo while working in a root shell which results in root having issued a command with disastrous effects. This is one reason why people who know the root password should avoid working in a root shell as far as possible. You might have noticed that (if you use default KDE configuration under Debian Lenny, at any rate) the root shell uses a different prompt (# instead of $) and has a different color--- that's to try to make sure that you don't forget that in some shell you are working as the root user, to lessen the chance of making a bad mistake.
As I understand it, you should only allow yourself to run via sudo a small number of privileged administrative commands which you really need to run often. You certainly shouldn't make your ordinary user arbitrary power.