Problems updating from the installation DVD disk

[Gus Sabina]

Hi:
I just bought an Acer Aspire 5749 laptop and installed Ubuntu 10.04 LTS 64-bit version. It happens both wired and wireless ethernet drivers are not included, so I searched and got a solution for this installation (I got a tarball file).
Now, in order to install the drivers, since there is no internet connection at all, I'm using following directions:

https://help.ubuntu.com/community/Repositories/Ubuntu#CD-ROM.2BAC8-DVD

to make sudo apt-get update working from the installation DVD instead of the internet.
However, even when "Installable from CD-ROM/DVD" option is checked, when I execute the update, I'm still getting errors such
w: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/....... "Could not resolve 'us.archive.ubuntu.com'

So, it seems that the installation DVD option is not being considered.

I would appreciate any help.

Thanks;
Gus

[Gus Sabina]

Ok. Now it seems it works, but when I try:
sudo apt-get install build-essential

it says build-essential is not in the installation disk.
What should I do?

Regards;
Gus