ok, BEFORE you try to get ANY packages, first reconfigure your sources. It's the first selection, at the top, when dselect opens up. When you select that, it will have a list of what sources can be had. I'm pretty sure it's called 'FTP', but it may be 'Internet'. The point is, you want to download the packages, so use the internet. It'll update the sources list, ask you if it's jiggy, and then try installing the packages.
EDIT: I'd HIGHLY suggest using Mandrake 9.1. Debian is slow and a little hard to learn. Mandrake installs a desktop and automatically loads it up for you when you boot up the computer. So it's easier to learn if you're familiar with Windows.