I am brand new to linux. I am try to install unbuntu 8.04 on a new
HP
LT (Vista). I have it partially installed (power on shows dual boot)
but ubuntu will not complete its boot. I get a series of messages
before it finally locks up.

My first question is did the Live CD ever boot or did you install from the
alternate CD? My second question would be, have you ever been able to get Ubuntu
to boot and what might you have been doing that had to do with modprobe?

I am not sure what you mean by power on shows dual boot. It is either dual boot
or it isn't. Dual boot means that you have two bootable operating systems, in
your case it would be Vista and Ubuntu 8.04. There should be a menu that
displays briefly so that you can choose which OS to boot, This menu is called
grub. Is that what you mean by power on?

If you have not had any success with dual booting then you probably don't have
anything to lose with re-installing, but I would try to be sure that the Live CD
boots and all hardware works properly first.

There are many factors that come into play for Ubuntu not to boot and we do not
have enough information to go on in order to resolve your issues.