not sure how this changes with 10.04, but in my experince with 8.04- you
will only give yourself a bit of work to do after installation if you are
not connected to the internet. You will have figure out how to manually set
up your /etc/network/interfaces file before you can ever connect to the
internet again and also manually add the default repositories and such to
your sources.list. network manager also may behave oddly.